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Simões de Almeida B, Torodii D, Moutzouri P, Emsley L. Barriers to resolution in 1H NMR of rotating solids. J Magn Reson 2023; 355:107557. [PMID: 37776831 DOI: 10.1016/j.jmr.2023.107557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 09/14/2023] [Accepted: 09/15/2023] [Indexed: 10/02/2023]
Abstract
The role of 1H solid-state NMR in structure elucidation of solids is becoming more preponderant, particularly as faster magic-angle spinning rates (MAS) become available which improve 1H detected assignment strategies. However, current 1H spectral resolution is still relatively poor, with linewidths of typically a few hundred Hz, even at the fastest rates available today. Here we detail and assess the factors limiting proton linewidths and line shapes in MAS experiments with five different samples, exemplifying the different sources of broadening that affect the residual linewidth. We disentangle the different contributions through one- and two-dimensional experiments: by using dilution to identify the contribution of ABMS; by using extensive deuteration to identify the dipolar contributions; and by using variable MAS rates to determine the ratio between homogeneous and inhomogeneous components. We find that the overall widths and the nature of the different contributions to the linewidths can vary very considerably. While we find that faster spinning always yields narrower lines and longer coherence lifetimes, we also find that for some resonances the dipolar contribution is no longer dominant at 100 kHz MAS. When the inhomogeneous sources of broadening, such as ABMS and chemical shift disorder, are dominant, two-dimensional 1H-1H correlation experiments yield better resolution for assignment. Particularly the extraction of the antidiagonal of a 2D peak will remove any correlated inhomogeneous broadening, giving substantially narrower 1H linewidths.
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Affiliation(s)
- Bruno Simões de Almeida
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Daria Torodii
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Pinelopi Moutzouri
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Lyndon Emsley
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland.
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2
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Osborn Popp TM, Matchett BT, Green RG, Chhabra I, Mumudi S, Bernstein AD, Perodeau JR, Nieuwkoop AJ. 3D-Printable centrifugal devices for biomolecular solid state NMR rotors. J Magn Reson 2023; 354:107524. [PMID: 37481918 PMCID: PMC10528322 DOI: 10.1016/j.jmr.2023.107524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 07/13/2023] [Accepted: 07/13/2023] [Indexed: 07/25/2023]
Abstract
The advent of magic angle spinning (MAS) rates exceeding 100 kHz has facilitated the acquisition of 1H-detected solid-state NMR spectra of biomolecules with high resolution. However, challenges can arise when preparing rotors for these experiments, due to the physical properties of biomolecular solid samples and the small dimensions of the rotors. In this study, we have designed 3D-printable centrifugal devices that facilitate efficient and consistent packing of crystalline protein slurries or viscous phospholipids into 0.7 mm rotors. We demonstrate the efficacy of these packing devices using 1H-detected solid state NMR at 105 kHz. In addition to devices for 0.7 mm rotors, we have also developed devices for other frequently employed rotor sizes and styles. We have made all our designs openly accessible, and we encourage their usage and ongoing development as a shared effort within the solid state NMR community.
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Affiliation(s)
- Thomas M Osborn Popp
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New, Jersey, Piscataway, NJ 08854, United States.
| | - Brandon T Matchett
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New, Jersey, Piscataway, NJ 08854, United States
| | - Rashawn G Green
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New, Jersey, Piscataway, NJ 08854, United States
| | - Insha Chhabra
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New, Jersey, Piscataway, NJ 08854, United States
| | - Smriti Mumudi
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New, Jersey, Piscataway, NJ 08854, United States
| | - Ashley D Bernstein
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New, Jersey, Piscataway, NJ 08854, United States
| | - Jacqueline R Perodeau
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New, Jersey, Piscataway, NJ 08854, United States
| | - Andrew J Nieuwkoop
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New, Jersey, Piscataway, NJ 08854, United States.
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3
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Golota NC, Fredin ZP, Banks DP, Preiss D, Bahri S, Patil P, Langford WK, Blackburn CL, Strand E, Michael B, Dastrup B, Nelson KA, Gershenfeld N, Griffin R. Diamond rotors. J Magn Reson 2023; 352:107475. [PMID: 37224586 PMCID: PMC10504678 DOI: 10.1016/j.jmr.2023.107475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 05/02/2023] [Accepted: 05/03/2023] [Indexed: 05/26/2023]
Abstract
The resolution of magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectra remains bounded by the spinning frequency, which is limited by the material strength of MAS rotors. Since diamond is capable of withstanding 1.5-2.5x greater MAS frequencies, compared to state-of-the art zirconia, we fabricated rotors from single crystal diamond. When combined with bearings optimized for spinning with helium gas, diamond rotors could achieve the highest MAS frequencies to date. Furthermore, the excellent microwave transmission properties and thermal conductivity of diamond could improve sensitivity enhancements in dynamic nuclear polarization (DNP) experiments. The fabrication protocol we report involves novel laser micromachining and produced rotors that presently spin at ωr/2π = 111.000 ± 0.004 kHz, with stable spinning up to 124 kHz, using N2 gas as the driving fluid. We present the first proton-detected 13C/15N MAS spectra recorded using diamond rotors, a critical step towards studying currently inaccessible ex-vivo protein samples with MAS NMR. Previously, the high aspect ratio of MAS rotors (∼10:1) precluded fabrication of MAS rotors from diamond.
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Affiliation(s)
- Natalie C Golota
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Zachary P Fredin
- Center for Bits and Atoms, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Daniel P Banks
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - David Preiss
- Center for Bits and Atoms, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Salima Bahri
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Prashant Patil
- Center for Bits and Atoms, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - William K Langford
- Center for Bits and Atoms, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Camron L Blackburn
- Center for Bits and Atoms, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Erik Strand
- Center for Bits and Atoms, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Brian Michael
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Blake Dastrup
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Keith A Nelson
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Neil Gershenfeld
- Center for Bits and Atoms, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Robert Griffin
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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4
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Lai A, Macdonald PM. Phospholipid lateral diffusion in the presence of cationic peptides as measured via 31P CODEX NMR. Biophys Chem 2023; 295:106964. [PMID: 36764129 DOI: 10.1016/j.bpc.2023.106964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 01/27/2023] [Accepted: 01/31/2023] [Indexed: 02/05/2023]
Abstract
The effects of two cationic peptides on phospholipid lateral diffusion in binary mixtures of POPC with various anionic phospholipids were measured via 31P CODEX NMR. Large unilamellar vesicles composed of POPC/POPG (70/30 mol/mol), or POPC/DOPS (70/30 mol/mol), or POPC/TOCL (85/15 mol/mol), or POPC/DOPA (50/50 mol/mol) were exposed to either polylysine (pLYS, N = 134 monomers) or KL-14 (KKLL KKAKK LLKKL), a model amphipathic helical peptide, in an amount corresponding to 80% neutralization of the anionic phospholipid charge by the cationic lysine residues. In the absence of added peptide, phospholipid lateral diffusion coefficients (all measured at 10 °C) increased with increasing reduced temperature (T-Tm). The POPC/DOPA mixture was an exception to this generalization, in that lateral diffusion for both components was far slower than any other mixture investigated, an effect attributed to intermolecular hydrogen bonding. The addition of pLYS or KL-14 decreased lateral diffusion in the POPC/DOPS LUV, but had minimal effects in the POPC/POPG LUV, indicating that ease of access of the cationic peptide residues to the anionic phospholipid groups was important. Both cationic peptides produced the opposite effect in the POPC/DOPA case, in that lateral diffusion increased significantly in their presence, with KL-14 being most effective. This latter observation was interpreted in terms of the electrostatic / H-bond model proposed by Kooijman et al. [Journal of Biological Chemistry, 282:11356-11,364, 2007] to describe the mechanism of interaction between the phosphomonoester head group of PA and the tertiary amine of lysine.
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Affiliation(s)
- Angel Lai
- Department of Chemistry, University of Toronto, Canada; Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Road North, Mississauga, Ontario L5L 1C6, Canada
| | - Peter M Macdonald
- Department of Chemistry, University of Toronto, Canada; Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Road North, Mississauga, Ontario L5L 1C6, Canada.
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5
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Gao C, Chen PH, Däpp A, Urban MA, Gunzenhauser R, Alaniva N, Barnes AB. Improving the sensitivity of MAS spheres using a 9.5 mm spherical shell with 219 μL sample volume spinning in a spherical solenoid coil. J Magn Reson 2022; 343:107305. [PMID: 36191440 DOI: 10.1016/j.jmr.2022.107305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 09/20/2022] [Accepted: 09/21/2022] [Indexed: 06/16/2023]
Abstract
Spherical rotors in magic angle spinning (MAS) nuclear magnetic resonance (NMR) experiments have potential advantages relative to cylindrical rotors in terms of ease of fabrication, low risk of rotor crash, easy sample exchange, and better microwave access. However, one major disadvantage so far of spherical rotors is poor NMR filling factor due to the small sample volume and large cylindrical radiofrequency (RF) coil. Here we present a novel NMR coil geometry in the form of a spherical coil. The spherical coil best fits the spherical sample to maximize sensitivity, while also providing excellent RF homogeneity. We further improve NMR sensitivity by employing a spherical shell as the rotor, thereby maximizing sample volume (219 μL in this case of 9.5 mm outer diameter spheres). The spinning gas is supplied by a 3D-printed ring stator external to the coil, thereby introducing a simplified form of MAS stators. In this apparatus, the RF field generated along the coil axis is perpendicular to the external magnetic field, regardless of rotor orientation. We observe a linear increase in sensitivity with increasing sample volume. We also simulate the RF performance of spherical and cylindrical solenoid coils with constant or variable pitch for spherical and cylindrical rotors, respectively. The simulation results show that spherical solenoid coils generate comparable B1 field intensities but have better homogeneity than cylindrical solenoid coils do.
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Affiliation(s)
- Chukun Gao
- Laboratory for Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Pin-Hui Chen
- Laboratory for Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Alexander Däpp
- Laboratory for Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Michael A Urban
- Laboratory for Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Ronny Gunzenhauser
- Laboratory for Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Nicholas Alaniva
- Laboratory for Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Alexander B Barnes
- Laboratory for Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland.
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6
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Xue K, Sarkar R, Tošner Z, Reif B. Field and magic angle spinning frequency dependence of proton resonances in rotating solids. Prog Nucl Magn Reson Spectrosc 2022; 130-131:47-61. [PMID: 36113917 DOI: 10.1016/j.pnmrs.2022.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 04/20/2022] [Accepted: 04/27/2022] [Indexed: 06/15/2023]
Abstract
Proton detection in solid state NMR is continuously developing and allows one to gain new insights in structural biology. Overall, this progress is a result of the synergy between hardware development, new NMR methodology and new isotope labeling strategies, to name a few factors. Even though current developments are rapid, it is worthwhile to summarize what can currently be achieved employing proton detection in biological solids. We illustrate this by analysing the signal-to-noise ratio (SNR) for spectra obtained for a microcrystalline α-spectrin SH3 domain protein sample by (i) employing different degrees of chemical dilution to replace protons by incorporating deuterons in different sites, by (ii) variation of the magic angle spinning (MAS) frequencies between 20 and 110 kHz, and by (iii) variation of the static magnetic field B0. The experimental SNR values are validated with numerical simulations employing up to 9 proton spins. Although in reality a protein would contain far more than 9 protons, in a deuterated environment this is a sufficient number to achieve satisfactory simulations consistent with the experimental data. The key results of this analysis are (i) with current hardware, deuteration is still necessary to record spectra of optimum quality; (ii) 13CH3 isotopomers for methyl groups yield the best SNR when MAS frequencies above 100 kHz are available; and (iii) sensitivity increases with a factor beyond B0 3/2 with the static magnetic field due to a transition of proton-proton dipolar interactions from a strong to a weak coupling limit.
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Affiliation(s)
- Kai Xue
- Max Planck Institute for Biophysical Chemistry, Department of NMR Based Structural Biology, Am Fassberg. 11, Goettingen, Germany
| | - Riddhiman Sarkar
- Helmholtz-Zentrum München (HMGU), Deutsches Forschungszentrum für Gesundheit und Umwelt, Ingolstädter Landstr. 1, 85764 Neuherberg, Germany; Munich Center for Integrated Protein Science (CIPS-M) at Department Chemie, Technische Universität München (TUM), Lichtenbergstr. 4, 85747 Garching, Germany
| | - Zdeněk Tošner
- Department of Chemistry, Faculty of Science, Charles University, Hlavova 8, 12842 Praha 2, Czech Republic
| | - Bernd Reif
- Helmholtz-Zentrum München (HMGU), Deutsches Forschungszentrum für Gesundheit und Umwelt, Ingolstädter Landstr. 1, 85764 Neuherberg, Germany; Munich Center for Integrated Protein Science (CIPS-M) at Department Chemie, Technische Universität München (TUM), Lichtenbergstr. 4, 85747 Garching, Germany.
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Abstract
Chromatin is a DNA-protein polymer that represents the functional form of the genome. The main building block of chromatin is the nucleosome, a structure that contains 147 base pairs of DNA and two copies each of the histone proteins H2A, H2B, H3 and H4. Previous work has shown that magic angle spinning (MAS) NMR spectroscopy can capture the nucleosome at high resolution although studies have been challenging due to low sensitivity, the presence of dynamic and rigid components, and the complex interaction networks of nucleosomes within the chromatin polymer. Here, we use dynamic nuclear polarization (DNP) to enhance the sensitivity of MAS NMR experiments of nucleosome arrays at 100 K and show that well-resolved 13C-13C MAS NMR correlations can be obtained much more efficiently. We evaluate the effect of temperature on the chemical shifts and linewidths in the spectra and demonstrate that changes are relatively minimal and clustered in regions of histone-DNA or histone-histone contacts. We also compare samples prepared with and without DNA and show that the low temperature 13C-13C correlations exhibit sufficient resolution to detect chemical shift changes and line broadening for residues that form the DNA-histone interface. On the other hand, we show that the measurement of DNP-enhanced 15N-13C histone-histone interactions within the nucleosome core is complicated by the natural 13C abundance network in the sample. Nevertheless, the enhanced sensitivity afforded by DNP can be used to detect long-range correlations between histone residues and DNA. Overall, our experiments demonstrate that DNP-enhanced MAS NMR spectroscopy of chromatin samples yields spectra with high resolution and sensitivity and can be used to capture functionally relevant protein-DNA interactions that have implications for gene regulation and genome organization.
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Affiliation(s)
| | | | - Galia T. Debelouchina
- Corresponding author: Galia Debelouchina, University of California, San Diego, Natural Sciences Building 4322, 9500 Gilman Dr., La Jolla, CA 92093, 858-534-3038,
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8
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Chandler B, Todd L, Smith SO. Magic angle spinning NMR of G protein-coupled receptors. Prog Nucl Magn Reson Spectrosc 2022; 128:25-43. [PMID: 35282868 PMCID: PMC10718405 DOI: 10.1016/j.pnmrs.2021.10.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 10/26/2021] [Accepted: 10/27/2021] [Indexed: 06/14/2023]
Abstract
G protein-coupled receptors (GPCRs) have a simple seven transmembrane helix architecture which has evolved to recognize a diverse number of chemical signals. The more than 800 GPCRs encoded in the human genome function as receptors for vision, smell and taste, and mediate key physiological processes. Consequently, these receptors are a major target for pharmaceuticals. Protein crystallography and electron cryo-microscopy have provided high resolution structures of many GPCRs in both active and inactive conformations. However, these structures have not sparked a surge in rational drug design, in part because GPCRs are inherently dynamic and the structural changes induced by ligand or drug binding to stabilize inactive or active conformations are often subtle rearrangements in packing or hydrogen-bonding interactions. NMR spectroscopy provides a sensitive probe of local structure and dynamics at specific sites within these receptors as well as global changes in receptor structure and dynamics. These methods can also capture intermediate states and conformations with low populations that provide insights into the activation pathways. We review the use of solid-state magic angle spinning NMR to address the structure and activation mechanisms of GPCRs. The focus is on the large and diverse class A family of receptors. We highlight three specific class A GPCRs in order to illustrate how solid-state, as well as solution-state, NMR spectroscopy can answer questions in the field involving how different GPCR classes and subfamilies are activated by their associated ligands, and how small molecule drugs can modulate GPCR activation.
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Affiliation(s)
- Bianca Chandler
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, United States.
| | - Lauren Todd
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, United States.
| | - Steven O Smith
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, United States.
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Banks D, Michael B, Golota N, Griffin RG. 3D-printed stators & drive caps for magic-angle spinning NMR. J Magn Reson 2022; 335:107126. [PMID: 34954545 PMCID: PMC8823525 DOI: 10.1016/j.jmr.2021.107126] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 12/04/2021] [Accepted: 12/06/2021] [Indexed: 06/14/2023]
Abstract
3D printing has evolved into an invaluable tool for rapid and cost-effective production of intricate parts. In this paper we describe 3D printing and other rapid prototyping methods to fabricate 3.2 mm stators and drive caps for use in magic angle spinning (MAS) NMR experiments. These components can be fabricated with the assistance of computer-aided design (CAD) software and at a fraction of the cost of commercial parts. Additionally, we show that the performance of these 3D printed stators and drive caps is comparable to commercially available systems and that they have significant advantages over their machined counterparts.
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Affiliation(s)
- Daniel Banks
- Francis Bitter Magnet Laboratory and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Brian Michael
- Francis Bitter Magnet Laboratory and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Natalie Golota
- Francis Bitter Magnet Laboratory and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Robert G Griffin
- Francis Bitter Magnet Laboratory and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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10
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Yang C, Ooi Tan K, Griffin RG. DNPSOUP: A simulation software package for dynamic nuclear polarization. J Magn Reson 2022; 334:107107. [PMID: 34894420 PMCID: PMC8819672 DOI: 10.1016/j.jmr.2021.107107] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Revised: 11/04/2021] [Accepted: 11/05/2021] [Indexed: 06/01/2023]
Abstract
Dynamic Nuclear Polarization Simulation Optimized with a Unified Propagator (DNPSOUP) is an open-source numerical software program that models spin dynamics for dynamic nuclear polarization (DNP). The software package utilizes a direct numerical approach using the inhomogeneous master equation to treat the time evolution of the spin density operator under coherent Hamiltonians and stochastic relaxation effects. Here we present the details of the theory behind the software, starting from the master equation, and arriving at characteristic operators for any section of density operator time-evolution. We then provide an overview of the DNPSOUP software architecture. The efficacy of the program is demonstrated by simulating DNP field profiles on small spin systems exploiting both continuous wave and time-domain DNP mechanisms. Examples include Zeeman field profiles for the solid effect, Overhauser effect, and cross effect, and microwave field profiles for NOVEL, off-resonance NOVEL, the integrated solid effect, the stretched solid effect, and TOP-DNP. The software should facilitate a better understanding of the DNP process, aid in the design of optimized DNP polarizing agents, and allow us to examine new pulsed DNP methods at conditions that are not currently experimentally accessible, especially at high magnetic fields with high-power microwave pulses.
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Affiliation(s)
- Chen Yang
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, United States; Aspen Technology, Inc., 20 Crosby Drive, Bedford, MA 01730, United States
| | - Kong Ooi Tan
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, United States; Laboratoire des Biomolécules, LBM, Département de Chimie, École Normale Supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France
| | - Robert G Griffin
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, United States.
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11
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Tognetti J, Trent Franks W, Gallo A, Lewandowski JR. Accelerating 15N and 13C R 1 and R 1ρ relaxation measurements by multiple pathway solid-state NMR experiments. J Magn Reson 2021; 331:107049. [PMID: 34508920 DOI: 10.1016/j.jmr.2021.107049] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 08/09/2021] [Accepted: 08/11/2021] [Indexed: 06/13/2023]
Abstract
Magic angle spinning (MAS) Solid-state NMR is a powerful technique to probe dynamics of biological systems at atomic resolution. R1 and R1ρ relaxation measurements can provide detailed insight on amplitudes and time scales of motions, especially when information from several different site-specific types of probes is combined. However, such experiments are time-consuming to perform. Shortening the time necessary to record relaxation data for different nuclei will greatly enhance practicality of such approaches. Here, we present staggered acquisition experiments to acquire multiple relaxation experiments from a single excitation to reduce the overall experimental time. Our strategy enables one to collect 15N and 13C relaxation data in a single experiment in a fraction of the time necessary for two separate experiments, with the same signal to noise ratio.
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Affiliation(s)
- Jacqueline Tognetti
- Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom; Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - W Trent Franks
- Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom; Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Angelo Gallo
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Józef R Lewandowski
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom.
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12
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Mentink-Vigier F, Dubroca T, Van Tol J, Sigurdsson ST. The distance between g-tensors of nitroxide biradicals governs MAS-DNP performance: The case of the bTurea family. J Magn Reson 2021; 329:107026. [PMID: 34246883 PMCID: PMC8316413 DOI: 10.1016/j.jmr.2021.107026] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Revised: 06/14/2021] [Accepted: 06/16/2021] [Indexed: 05/20/2023]
Abstract
Bis-nitroxide radicals are common polarizing agents (PA), used to enhance the sensitivity of solid-state NMR experiments via Magic Angle Spinning Dynamic Nuclear Polarization (MAS-DNP). These biradicals can increase the proton spin polarization through the Cross-Effect (CE) mechanism, which requires PAs with at least two unpaired electrons. The relative orientation of the bis-nitroxide moieties is critical to ensure efficient polarization transfer. Recently, we have defined a new quantity, the distance between g-tensors, that correlates the relative orientation of the nitroxides with the ability to polarize the surrounding nuclei. Here we analyse experimentally and theoretically a series of biradicals belonging to the bTurea family, namely bcTol, AMUPol and bcTol-M. They differ by the degree of substitution on the urea bridge that connects the two nitroxides. Using quantitative simulations developed for moderate MAS frequencies, we show that these modifications mostly affect the relative orientations of the nitroxide, i.e. the length and distribution of the distance between the g-tensors, that in turn impacts both the steady state nuclear polarization/depolarization as well as the build-up times. The doubly substituted urea bridge favours a large distance between the g-tensors, which enables bcTol-M to provide ∊on/off>200 at 14.1 T/600 MHz/395 GHz with build-up times of 3.8 s using a standard homogenous solution. The methodology described herein was used to show how the conformation of the spirocyclic rings flanking the nitroxide function in the recently described c- and o-HydrOPol affects the distance between the g-tensors and thereby polarization performance.
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Affiliation(s)
- Frédéric Mentink-Vigier
- National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Dr, Tallahassee, FL 32310, United States.
| | - Thierry Dubroca
- National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Dr, Tallahassee, FL 32310, United States
| | - Johan Van Tol
- National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Dr, Tallahassee, FL 32310, United States
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13
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Bertarello A, Berruyer P, Skantze U, Sardana S, Sardana M, Elmore CS, Schade M, Chiarparin E, Schantz S, Emsley L. Quantification of magic angle spinning dynamic nuclear polarization NMR spectra. J Magn Reson 2021; 329:107030. [PMID: 34245958 DOI: 10.1016/j.jmr.2021.107030] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 06/22/2021] [Accepted: 06/25/2021] [Indexed: 06/13/2023]
Abstract
Dynamic nuclear polarization (DNP) allows to dramatically enhance the sensitivity of magic angle spinning nuclear magnetic resonance (MAS NMR). DNP experiments usually rely on the detection of low-γ nuclei hyperpolarized from 1H with the use of cross polarization (CP), which assures more efficient signal enhancement. However, CP is usually not quantitative. Here we determine the quantification performance of three different approaches used in MAS NMR, (conventional CP, variable contact time CP, and multiple-contact CP) under DNP conditions, and we show that absolute quantification in MAS DNP NMR is possible, with errors below 10%.
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Affiliation(s)
- Andrea Bertarello
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Pierrick Berruyer
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Urban Skantze
- Advanced Drug Delivery, Pharmaceutical Science, AstraZeneca, Gothenburg, Sweden
| | - Samiksha Sardana
- Early Chemical Development, Pharmaceutical Science, R&D, AstraZeneca, Gothenburg, Sweden
| | - Malvika Sardana
- Early Chemical Development, Pharmaceutical Science, R&D, AstraZeneca, Gothenburg, Sweden
| | - Charles S Elmore
- Early Chemical Development, Pharmaceutical Science, R&D, AstraZeneca, Gothenburg, Sweden
| | - Markus Schade
- Chemistry, Oncology R&D, AstraZeneca, Cambridge, United Kingdom
| | | | - Staffan Schantz
- Oral Product Development, Pharmaceutical Technology & Development, Operations, AstraZeneca, Gothenburg, Sweden
| | - Lyndon Emsley
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
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14
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Silvers R, Eddy MT. NMR Spectroscopic Studies of Ion Channels in Lipid Bilayers: Sample Preparation Strategies Exemplified by the Voltage Dependent Anion Channel. Methods Mol Biol 2021; 2302:201-17. [PMID: 33877629 DOI: 10.1007/978-1-0716-1394-8_11] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
We describe approaches for the preparation of membrane proteins in detergent micelles and lipid bilayers for solution and magic angle spinning NMR studies, respectively, as exemplified by the human voltage dependent anion channel 1 (hVDAC1). Here, we report protocols for the preparation of homogenous samples of recombinant hVDAC1 in detergent micelles and lipid two-dimensional crystals yielding high resolution NMR spectra. Procedures are described for the recombinant production of stable-isotope labeled hVDAC1 in E. coli, the isolation of hVDAC1 from inclusion bodies and the refolding into detergent micelles, as well as the reconstitution of hVDAC1 into lipids to form 2D crystals.
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15
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Moutzouri P, Simões de Almeida B, Emsley L. Fast remote correlation experiments for 1H homonuclear decoupling in solids. J Magn Reson 2020; 321:106856. [PMID: 33157355 DOI: 10.1016/j.jmr.2020.106856] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 10/19/2020] [Accepted: 10/20/2020] [Indexed: 06/11/2023]
Abstract
In 1H MAS spectra, the residual homogeneous broadening under MAS is due to a combination of higher-order shifts and splittings. We have recently shown how the two-dimensional anti-z-COSY experiment can be used for the removal of the splittings. However, this requires spectra with high resolution in the indirect dimension (t1), leading to experiment times of hours. Here, we show how anti-z-COSY can be adapted to be combined with the two-dimensional one pulse (TOP) transformation which leads to significantly reduced experimental time while retaining the line narrowing effect. The experiment is demonstrated on a powdered sample of L-histidine monohydrochloride monohydrate, where the new TAZ-COSY sequence at 100 kHz MAS, yields between a factor 1.6 and 2.3 increase in resolution compared with the equivalent one-pulse experiment, in just 20 min. The same methodology is also adapted for the acquisition of liquid state 1H homodecoupled data, and an example is given for testosterone.
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Affiliation(s)
- Pinelopi Moutzouri
- Institut des Sciences et Ingéniere Chimiques, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Bruno Simões de Almeida
- Institut des Sciences et Ingéniere Chimiques, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Lyndon Emsley
- Institut des Sciences et Ingéniere Chimiques, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
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16
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Kelly JE, Chrissian C, Stark RE. Tailoring NMR experiments for structural characterization of amorphous biological solids: A practical guide. Solid State Nucl Magn Reson 2020; 109:101686. [PMID: 32896783 PMCID: PMC7530138 DOI: 10.1016/j.ssnmr.2020.101686] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 07/30/2020] [Accepted: 08/04/2020] [Indexed: 05/12/2023]
Abstract
Many interesting solid-state targets for biological research do not form crystalline structures; these materials include intrinsically disordered proteins, plant biopolymer composites, cell-wall polysaccharides, and soil organic matter. The absence of aligned repeating structural elements and atomic-level rigidity presents hurdles to achieving structural elucidation and obtaining functional insights. We describe strategies for adapting several solid-state NMR methods to determine the molecular structures and compositions of these amorphous biosolids. The main spectroscopic problems in studying amorphous structures by NMR are over/under-sampling of the spin signals and spectral complexity. These problems arise in part because amorphous biosolids typically contain a mix of rigid and mobile domains, making it difficult to select a single experiment or set of acquisition conditions that fairly represents all nuclear spins in a carbon-based organic sample. These issues can be addressed by running hybrid experiments, such as using direct excitation alongside cross polarization-based methods, to develop a more holistic picture of the macromolecular system. In situations of spectral crowding or overlap, the structural elucidation strategy can be further assisted by coupling 13C spins to nuclei such as 15N, filtering out portions of the spectrum, highlighting individual moieties of interest, and adding a second or third spectral dimension to an NMR experiment in order to spread out the resonances and link them pairwise through space or through bonds. We discuss practical aspects and illustrations from the recent literature for 1D experiments that use cross or direct polarization and both homo- and heteronuclear 2D and 3D solid-state NMR experiments.
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Affiliation(s)
- John E Kelly
- Department of Chemistry and Biochemistry, City College of New York and CUNY Institute for Macromolecular Assemblies, New York, NY, 10031, USA
| | - Christine Chrissian
- Department of Chemistry and Biochemistry, City College of New York and CUNY Institute for Macromolecular Assemblies, New York, NY, 10031, USA; Ph.D. Program in Biochemistry, The Graduate Center of the City University of New York, New York, NY, 10016, USA
| | - Ruth E Stark
- Department of Chemistry and Biochemistry, City College of New York and CUNY Institute for Macromolecular Assemblies, New York, NY, 10031, USA; Ph.D. Program in Biochemistry, The Graduate Center of the City University of New York, New York, NY, 10016, USA; Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, NY, 10016, USA.
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17
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Hassan A, Quinn CM, Struppe J, Sergeyev IV, Zhang C, Guo C, Runge B, Theint T, Dao HH, Jaroniec CP, Berbon M, Lends A, Habenstein B, Loquet A, Kuemmerle R, Perrone B, Gronenborn AM, Polenova T. Sensitivity boosts by the CPMAS CryoProbe for challenging biological assemblies. J Magn Reson 2020; 311:106680. [PMID: 31951864 PMCID: PMC7060763 DOI: 10.1016/j.jmr.2019.106680] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 12/19/2019] [Accepted: 12/21/2019] [Indexed: 06/09/2023]
Abstract
Despite breakthroughs in MAS NMR hardware and experimental methodologies, sensitivity remains a major challenge for large and complex biological systems. Here, we report that 3-4 fold higher sensitivities can be obtained in heteronuclear-detected experiments, using a novel HCN CPMAS probe, where the sample coil and the electronics operate at cryogenic temperatures, while the sample is maintained at ambient temperatures (BioSolids CryoProbe™). Such intensity enhancements permit recording 2D and 3D experiments that are otherwise time-prohibitive, such as 2D 15N-15N proton-driven spin diffusion and 15N-13C double cross polarization to natural abundance carbon experiments. The benefits of CPMAS CryoProbe-based experiments are illustrated for assemblies of kinesin Kif5b with microtubules, HIV-1 capsid protein assemblies, and fibrils of human Y145Stop and fungal HET-s prion proteins - demanding systems for conventional MAS solid-state NMR and excellent reference systems in terms of spectral quality. We envision that this probe technology will be beneficial for a wide range of applications, especially for biological systems suffering from low intrinsic sensitivity and at physiological temperatures.
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Affiliation(s)
- Alia Hassan
- Bruker Biospin Corporation, Fällanden, Switzerland.
| | - Caitlin M Quinn
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, United States
| | - Jochem Struppe
- Bruker Biospin Corporation, 15 Fortune Drive, Billerica, MA, United States
| | - Ivan V Sergeyev
- Bruker Biospin Corporation, 15 Fortune Drive, Billerica, MA, United States
| | - Chunting Zhang
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, United States
| | - Changmiao Guo
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, United States
| | - Brent Runge
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, United States; Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Theint Theint
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, United States
| | - Hanh H Dao
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, United States
| | - Christopher P Jaroniec
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, United States
| | - Mélanie Berbon
- CNRS, CBMN, UMR5248, University of Bordeaux, F-33600 Pessac, France
| | - Alons Lends
- CNRS, CBMN, UMR5248, University of Bordeaux, F-33600 Pessac, France
| | | | - Antoine Loquet
- CNRS, CBMN, UMR5248, University of Bordeaux, F-33600 Pessac, France
| | | | | | - Angela M Gronenborn
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States; Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 Fifth Ave., Pittsburgh, PA, United States.
| | - Tatyana Polenova
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, United States; Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States.
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18
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Chen PH, Gao C, Barnes AB. Perspectives on microwave coupling into cylindrical and spherical rotors with dielectric lenses for magic angle spinning dynamic nuclear polarization. J Magn Reson 2019; 308:106518. [PMID: 31345770 DOI: 10.1016/j.jmr.2019.07.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 07/03/2019] [Accepted: 07/05/2019] [Indexed: 06/10/2023]
Abstract
Continuous wave dynamic nuclear polarization (DNP) increases the sensitivity of NMR, yet intense microwave fields are required to transition magic angle spinning (MAS) DNP to the time domain. Here we describe and analyze Teflon lenses for cylindrical and spherical MAS rotors that focus microwave power and increase the electron Rabi frequency, ν1s. Using a commercial simulation package, we solve the Maxwell equations and determine the propagation and focusing of millimeter waves (198 GHz). We then calculate the microwave intensity in a time-independent fashion to compute the ν1s. With a nominal microwave power input of 5 W, the average ν1s is 0.38 MHz within a 22 μL sample volume in a 3.2 mm outer diameter (OD) cylindrical rotor without a Teflon lens. Decreasing the sample volume to 3 μL and focusing the microwave beam with a Teflon lens increases the ν1s to 1.5 MHz. Microwave polarization and intensity perturbations associated with diffraction through the radiofrequency coil, losses from penetration through the rotor wall, and mechanical limitations of the separation between the lens and sample are significant challenges to improving microwave coupling in MAS DNP instrumentation. To overcome these issues, we introduce a novel focusing strategy using dielectric microwave lenses installed within spinning rotors. One such 9.5 mm OD cylindrical rotor assembly implements a Teflon focusing lens to increase the ν1s to 2.7 MHz within a 2 μL sample. Further, to access high spinning frequencies while also increasing ν1s, we analyze microwave coupling into MAS spheres. For 9.5 mm OD spherical rotors, we compute a ν1s of 0.36 MHz within a sample volume of 161 μL, and 2.5 MHz within a 3 μL sample placed at the focal point of a novel double lens insert. We conclude with an analysis and discussion of sub-millimeter diamond spherical rotors for time domain DNP at spinning frequencies >100 kHz. Sub-millimeter spherical rotors better overlap a tightly focused microwave beam, resulting in a ν1s of 2.2 MHz. Lastly, we propose that sub-millimeter dielectric spherical microwave resonators will provide a means to substantially improve electron spin control in the future.
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Affiliation(s)
- Pin-Hui Chen
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA; Department of Physics, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Chukun Gao
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Alexander B Barnes
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA.
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19
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Gao C, Alaniva N, Saliba EP, Sesti EL, Judge PT, Scott FJ, Halbritter T, Sigurdsson ST, Barnes AB. Frequency-chirped dynamic nuclear polarization with magic angle spinning using a frequency-agile gyrotron. J Magn Reson 2019; 308:106586. [PMID: 31525550 DOI: 10.1016/j.jmr.2019.106586] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 08/15/2019] [Accepted: 08/28/2019] [Indexed: 06/10/2023]
Abstract
We demonstrate that frequency-chirped dynamic nuclear polarization (DNP) with magic angle spinning (MAS) improves the enhancement of nuclear magnetic resonance (NMR) signal beyond that of continuous-wave (CW) DNP. Using a custom, frequency-agile gyrotron we implemented frequency-chirped DNP using the TEMTriPol-1 biradical, with MAS NMR at 7 T. Frequency-chirped microwaves yielded a DNP enhancement of 137, an increase of 19% compared to 115 recorded with CW. The chirps were 120 MHz-wide and centered over the trityl resonance, with 7 W microwave power incident on the sample (estimated 0.4 MHz electron spin Rabi frequency). We describe in detail the design and fabrication of the frequency-agile gyrotron used for frequency-chirped MAS DNP. Improvements to the interaction cavity and internal mode converter yielded efficient microwave generation and mode conversion, achieving >10 W output power over a 335 MHz bandwidth with >110 W peak power. Frequency-chirped DNP with MAS is expected to have a significant impact on the future of magnetic resonance.
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Affiliation(s)
- Chukun Gao
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA; Physical Chemistry, ETH-Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
| | - Nicholas Alaniva
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA; Physical Chemistry, ETH-Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
| | - Edward P Saliba
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA; Physical Chemistry, ETH-Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
| | - Erika L Sesti
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Patrick T Judge
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA; Department of Biochemistry, Biophysics & Structural Biology, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Faith J Scott
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Thomas Halbritter
- University of Iceland, Department of Chemistry, Science Institute, Dunhaga 3, 107 Reykjavik, Iceland
| | - Snorri Th Sigurdsson
- University of Iceland, Department of Chemistry, Science Institute, Dunhaga 3, 107 Reykjavik, Iceland
| | - Alexander B Barnes
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA; Physical Chemistry, ETH-Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland.
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20
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Russell RW, Fritz MP, Kraus J, Quinn CM, Polenova T, Gronenborn AM. Accuracy and precision of protein structures determined by magic angle spinning NMR spectroscopy: for some 'with a little help from a friend'. J Biomol NMR 2019; 73:333-346. [PMID: 30847635 PMCID: PMC6693955 DOI: 10.1007/s10858-019-00233-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 02/06/2019] [Indexed: 06/09/2023]
Abstract
We present a systematic investigation into the attainable accuracy and precision of protein structures determined by heteronuclear magic angle spinning solid-state NMR for a set of four proteins of varied size and secondary structure content. Structures were calculated using synthetically generated random sets of C-C distances up to 7 Å at different degrees of completeness. For single-domain proteins, 9-15 restraints per residue are sufficient to derive an accurate model structure, while maximum accuracy and precision are reached with over 15 restraints per residue. For multi-domain proteins and protein assemblies, additional information on domain orientations, quaternary structure and/or protein shape is needed. As demonstrated for the HIV-1 capsid protein assembly, this can be accomplished by integrating MAS NMR with cryoEM data. In all cases, inclusion of TALOS-derived backbone torsion angles improves the accuracy for small number of restraints, while no further increases are noted for restraint completeness above 40%. In contrast, inclusion of TALOS-derived torsion angle restraints consistently increases the precision of the structural ensemble at all degrees of distance restraint completeness.
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Affiliation(s)
- Ryan W Russell
- Department of Chemistry and Biochemistry, University of Delaware, 19716, Newark, DE, USA
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave, 15261, Pittsburgh, PA, USA
| | - Matthew P Fritz
- Department of Chemistry and Biochemistry, University of Delaware, 19716, Newark, DE, USA
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave, 15261, Pittsburgh, PA, USA
| | - Jodi Kraus
- Department of Chemistry and Biochemistry, University of Delaware, 19716, Newark, DE, USA
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave, 15261, Pittsburgh, PA, USA
| | - Caitlin M Quinn
- Department of Chemistry and Biochemistry, University of Delaware, 19716, Newark, DE, USA
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave, 15261, Pittsburgh, PA, USA
| | - Tatyana Polenova
- Department of Chemistry and Biochemistry, University of Delaware, 19716, Newark, DE, USA.
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave, 15261, Pittsburgh, PA, USA.
| | - Angela M Gronenborn
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave, 15261, Pittsburgh, PA, USA.
- Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 Fifth Ave, 15261, Pittsburgh, PA, USA.
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21
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Gao C, Judge PT, Sesti EL, Price LE, Alaniva N, Saliba EP, Albert BJ, Soper NJ, Chen PH, Barnes AB. Four millimeter spherical rotors spinning at 28 kHz with double-saddle coils for cross polarization NMR. J Magn Reson 2019; 303:1-6. [PMID: 30978570 DOI: 10.1016/j.jmr.2019.03.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 03/07/2019] [Accepted: 03/20/2019] [Indexed: 06/09/2023]
Abstract
Spherical rotors in magic angle spinning (MAS) experiments have significant advantages over traditional cylindrical rotors including simplified spinning implementation, easy sample exchange, more efficient microwave coupling for dynamic nuclear polarization (DNP), and feasibility of downscaling to access higher spinning frequencies. Here, we implement spherical rotors with 4 mm outside diameter (o.d.) and demonstrate spinning >28 kHz using a single aperture for spinning gas. We show a modified stator geometry to improve fiber optic detection, increase NMR filling factor, and improve alignment for sample exchange and microwave irradiation. Higher NMR Rabi frequencies were obtained using smaller radiofrequency (RF) coils on small-diameter spherical rotors, compared to our previous implementation of MAS spheres with an o.d. of 9.5 mm. We report nutation fields of 110 kHz on 13C with 820 W of input power and 100 kHz on 1H with 800 W of input power. Proton decoupling fields of 78 kHz were applied over 20 ms of signal acquisition without any sign of arcing. Compared to our initial demonstration of a split coil for 9.5 mm spheres, this current implementation of a double-saddle coil inductor for 4 mm spheres not only intensifies the RF fields, but also improves RF homogeneity. We achieve an 810°/90° nutation intensity ratio of 0.84 at 300.197 MHz (1H). We also show electromagnetic simulations predicting a nearly 3-fold improvement in electron Rabi frequency of 0.99 MHz (with 4 mm spheres) compared to 0.38 MHz (with 3.2 mm cylinders), with 5 W of incident microwave power. Further improvements in magnetic resonance spin control are expected as RF inductors and microwave coupling are optimized for spherical rotors and scaled down to the micron scale.
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Affiliation(s)
- Chukun Gao
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Patrick T Judge
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA; Department of Biochemistry, Biophysics & Structural Biology, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Erika L Sesti
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Lauren E Price
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Nicholas Alaniva
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Edward P Saliba
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Brice J Albert
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Nathan J Soper
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Pin-Hui Chen
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA; Department of Physics, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Alexander B Barnes
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA.
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22
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Purea A, Reiter C, Dimitriadis AI, de Rijk E, Aussenac F, Sergeyev I, Rosay M, Engelke F. Improved waveguide coupling for 1.3 mm MAS DNP probes at 263 GHz. J Magn Reson 2019; 302:43-49. [PMID: 30953925 DOI: 10.1016/j.jmr.2019.03.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 03/26/2019] [Accepted: 03/27/2019] [Indexed: 06/09/2023]
Abstract
We consider the geometry of a radially irradiated microwave beam in MAS DNP NMR probes and its impact on DNP enhancement. Two related characteristic features are found to be relevant: (i) the focus of the microwave beam on the DNP MAS sample and (ii) the microwave magnetic field magnitude in the sample. We present a waveguide coupler setup that enables us to significantly improve beam focus and field magnitude in 1.3 mm MAS DNP probes at a microwave frequency of 263 GHz, which results in an increase of the DNP enhancement by a factor of 2 compared to previous standard hardware setups. We discuss the implications of improved coupling and its potential to enable cutting-edge applications, such as pulsed high-field DNP and the use of low-power solid-state microwave sources.
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23
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Gopinath T, Wang S, Lee J, Aihara H, Veglia G. Hybridization of TEDOR and NCX MAS solid-state NMR experiments for simultaneous acquisition of heteronuclear correlation spectra and distance measurements. J Biomol NMR 2019; 73:141-153. [PMID: 30805819 PMCID: PMC6526076 DOI: 10.1007/s10858-019-00237-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 02/12/2019] [Indexed: 05/05/2023]
Abstract
Magic angle spinning (MAS) solid-state NMR (ssNMR) spectroscopy is a major technique for the characterization of the structural dynamics of biopolymers at atomic resolution. However, the intrinsic low sensitivity of this technique poses significant limitations to its routine application in structural biology. Here we achieve substantial savings in experimental time using a new subclass of Polarization Optimized Experiments (POEs) that concatenate TEDOR and SPECIFIC-CP transfers into a single pulse sequence. Specifically, we designed new 2D and 3D experiments (2D TEDOR-NCX, 3D TEDOR-NCOCX, and 3D TEDOR-NCACX) to obtain distance measurements and heteronuclear chemical shift correlations for resonance assignments using only one experiment. We successfully tested these experiments on N-Acetyl-Val-Leu dipeptide, microcrystalline U-13C,15N ubiquitin, and single- and multi-span membrane proteins reconstituted in lipid membranes. These pulse sequences can be implemented on any ssNMR spectrometer equipped with standard solid-state hardware using only one receiver. Since these new POEs speed up data acquisition considerably, we anticipate their broad application to fibrillar, microcrystalline, and membrane-bound proteins.
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Affiliation(s)
- T Gopinath
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, 6-155 Jackson Hall, Minneapolis, MN, 55455, USA
| | - Songlin Wang
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, 6-155 Jackson Hall, Minneapolis, MN, 55455, USA
| | - John Lee
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, 6-155 Jackson Hall, Minneapolis, MN, 55455, USA
| | - Hideki Aihara
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, 6-155 Jackson Hall, Minneapolis, MN, 55455, USA
| | - Gianluigi Veglia
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, 6-155 Jackson Hall, Minneapolis, MN, 55455, USA.
- Department of Chemistry, University of Minnesota, Minneapolis, MN, 55455, USA.
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24
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Aharoni T, Goldbourt A. Rapid automated determination of chemical shift anisotropy values in the carbonyl and carboxyl groups of fd-y21m bacteriophage using solid state NMR. J Biomol NMR 2018; 72:55-67. [PMID: 30141148 DOI: 10.1007/s10858-018-0206-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 08/17/2018] [Indexed: 06/08/2023]
Abstract
Determination of chemical shift anisotropy (CSA) in immobilized proteins and protein assemblies is one of several tools to determine protein dynamics on the timescales of microseconds and faster. The large CSA values of C=O groups in the rigid limit makes them in particular attractive for measurements of large amplitude motions, or their absence. In this study, we implement a 3D R-symmetry-based sequence that recouples the second spatial component of the 13C CSA with the corresponding isotropic 13C'-13C cross-peaks in order to probe backbone and sidechain dynamics in an intact fd-y21m filamentous phage viral capsid. The assignment of the isotropic cross-peaks and the analysis were conducted automatically using a new software named 'Raven'. The software can be utilized to auto-assign any 2D 13C-13C or 15N-13C spectrum given a previously-determined assignment table and generates simultaneously all intensity curves acquired in the third dimension. Here, all CSA spectra were automatically generated, and subsequently matched against a simulated set of CSA curves to yield their values. For the multi-copy, 50-residue-long protein capsid of fd-y21m, the backbone of the helical region is rigid, with reduced CSA values of ~ 12.5 kHz (~ 83 ppm). The N-terminus shows motionally-averaged CSA lineshapes and the carboxylic sidechain groups of four residues indicate large amplitude motions for D4, D5, D12 and E20. The current results further strengthen our previous studies of 15N CSA values and are in agreement with qualitative analysis of 13C-13C dipolar build-up curves, which were automatically obtained using our software. Our automated analysis technique is general and can be applied to study protein structure and dynamics, with data resulting from experiments that probe different variables such as relaxation rates and scaled anisotropic interactions.
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Affiliation(s)
- Tom Aharoni
- School of Chemistry, The Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Ramat Aviv, 6997801, Tel Aviv, Israel
| | - Amir Goldbourt
- School of Chemistry, The Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Ramat Aviv, 6997801, Tel Aviv, Israel.
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25
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Jaudzems K, Polenova T, Pintacuda G, Oschkinat H, Lesage A. DNP NMR of biomolecular assemblies. J Struct Biol 2018; 206:90-98. [PMID: 30273657 DOI: 10.1016/j.jsb.2018.09.011] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 09/13/2018] [Accepted: 09/27/2018] [Indexed: 11/30/2022]
Abstract
Dynamic Nuclear Polarization (DNP) is an effective approach to alleviate the inherently low sensitivity of solid-state NMR (ssNMR) under magic angle spinning (MAS) towards large-sized multi-domain complexes and assemblies. DNP relies on a polarization transfer at cryogenic temperatures from unpaired electrons to adjacent nuclei upon continuous microwave irradiation. This is usually made possible via the addition in the sample of a polarizing agent. The first pioneering experiments on biomolecular assemblies were reported in the early 2000s on bacteriophages and membrane proteins. Since then, DNP has experienced tremendous advances, with the development of extremely efficient polarizing agents or with the introduction of new microwaves sources, suitable for NMR experiments at very high magnetic fields (currently up to 900 MHz). After a brief introduction, several experimental aspects of DNP enhanced NMR spectroscopy applied to biomolecular assemblies are discussed. Recent demonstration experiments of the method on viral capsids, the type III and IV bacterial secretion systems, ribosome and membrane proteins are then described.
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Affiliation(s)
- Kristaps Jaudzems
- Centre de RMN à Très Hauts Champs, Institut des Sciences Analytiques (UMR 5280 - CNRS, ENS Lyon, UCB Lyon 1), Université de Lyon, 5 rue de la Doua, 69100 Villeurbanne, France
| | - Tatyana Polenova
- Department of Chemistry and Biochemistry, University of Delaware, 163 The Green, DE 19716, USA
| | - Guido Pintacuda
- Centre de RMN à Très Hauts Champs, Institut des Sciences Analytiques (UMR 5280 - CNRS, ENS Lyon, UCB Lyon 1), Université de Lyon, 5 rue de la Doua, 69100 Villeurbanne, France
| | - Hartmut Oschkinat
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie im Forschungsverbund Berlin e.V. (FMP), Campus Berlin-Buch Robert-Roessle-Str. 10 13125 Berlin, Germany
| | - Anne Lesage
- Centre de RMN à Très Hauts Champs, Institut des Sciences Analytiques (UMR 5280 - CNRS, ENS Lyon, UCB Lyon 1), Université de Lyon, 5 rue de la Doua, 69100 Villeurbanne, France
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26
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Gopinath T, Veglia G. Probing membrane protein ground and conformationally excited states using dipolar- and J-coupling mediated MAS solid state NMR experiments. Methods 2018; 148:115-122. [PMID: 30012515 PMCID: PMC6428079 DOI: 10.1016/j.ymeth.2018.07.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 07/10/2018] [Accepted: 07/11/2018] [Indexed: 12/25/2022] Open
Abstract
The intrinsic conformational plasticity of membrane proteins directly influences the magnitude of the orientational-dependent NMR interactions such as dipolar couplings (DC) and chemical shift anisotropy (CSA). As a result, the conventional cross-polarization (CP)-based techniques mainly capture the more rigid regions of membrane proteins, while the most dynamic regions are essentially invisible. Nonetheless, dynamic regions can be detected using experiments in which polarization transfer takes place via J-coupling interactions. Here, we review our recent efforts to develop single and dual acquisition pulse sequences with either 1H or 13C detection that utilize both DC and J-coupling mediated transfer to detect both rigid and mobile regions of membrane proteins in native-like lipid environments. We show the application of these new methods for studying the conformational equilibrium of a single-pass membrane protein, phospholamban, which regulates the calcium transport across the sarcoplasmic reticulum (SR) membrane by interacting with the SR Ca2+-ATPase. We anticipate that these methods will be ideal to portray the complex dynamics of membrane proteins in their native environments.
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Affiliation(s)
- T Gopinath
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, United States
| | - Gianluigi Veglia
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, United States; Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, United States.
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27
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Martin RW, Kelly JE, Kelz JI. Advances in instrumentation and methodology for solid-state NMR of biological assemblies. J Struct Biol 2018; 206:73-89. [PMID: 30205196 DOI: 10.1016/j.jsb.2018.09.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 07/08/2018] [Accepted: 09/06/2018] [Indexed: 01/11/2023]
Abstract
Many advances in instrumentation and methodology have furthered the use of solid-state NMR as a technique for determining the structures and studying the dynamics of molecules involved in complex biological assemblies. Solid-state NMR does not require large crystals, has no inherent size limit, and with appropriate isotopic labeling schemes, supports solving one component of a complex assembly at a time. It is complementary to cryo-EM, in that it provides local, atomic-level detail that can be modeled into larger-scale structures. This review focuses on the development of high-field MAS instrumentation and methodology; including probe design, benchmarking strategies, labeling schemes, and experiments that enable the use of quadrupolar nuclei in biomolecular NMR. Current challenges facing solid-state NMR of biological assemblies and new directions in this dynamic research area are also discussed.
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Affiliation(s)
- Rachel W Martin
- Department of Chemistry, University of California, Irvine 92697-2025, United States; Department of Molecular Biology and Biochemistry, University of California, Irvine 92697-3900, United States.
| | - John E Kelly
- Department of Chemistry, University of California, Irvine 92697-2025, United States
| | - Jessica I Kelz
- Department of Chemistry, University of California, Irvine 92697-2025, United States
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28
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Krushelnitsky A, Gauto D, Rodriguez Camargo DC, Schanda P, Saalwächter K. Microsecond motions probed by near-rotary-resonance R 1ρ15N MAS NMR experiments: the model case of protein overall-rocking in crystals. J Biomol NMR 2018; 71:53-67. [PMID: 29845494 PMCID: PMC5986846 DOI: 10.1007/s10858-018-0191-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 05/26/2018] [Indexed: 05/27/2023]
Abstract
Solid-state near-rotary-resonance measurements of the spin-lattice relaxation rate in the rotating frame (R1ρ) is a powerful NMR technique for studying molecular dynamics in the microsecond time scale. The small difference between the spin-lock (SL) and magic-angle-spinning (MAS) frequencies allows sampling very slow motions, at the same time it brings up some methodological challenges. In this work, several issues affecting correct measurements and analysis of 15N R1ρ data are considered in detail. Among them are signal amplitude as a function of the difference between SL and MAS frequencies, "dead time" in the initial part of the relaxation decay caused by transient spin-dynamic oscillations, measurements under HORROR condition and proper treatment of the multi-exponential relaxation decays. The multiple 15N R1ρ measurements at different SL fields and temperatures have been conducted in 1D mode (i.e. without site-specific resolution) for a set of four different microcrystalline protein samples (GB1, SH3, MPD-ubiquitin and cubic-PEG-ubiquitin) to study the overall protein rocking in a crystal. While the amplitude of this motion varies very significantly, its correlation time for all four sample is practically the same, 30-50 μs. The amplitude of the rocking motion correlates with the packing density of a protein crystal. It has been suggested that the rocking motion is not diffusive but likely a jump-like dynamic process.
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Affiliation(s)
| | - Diego Gauto
- Institut de Biologie Structurale (IBS), Grenoble Cedex 9, France
| | | | - Paul Schanda
- Institut de Biologie Structurale (IBS), Grenoble Cedex 9, France
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29
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Collier KA, Sengupta S, Espinosa CA, Kelly JE, Kelz JI, Martin RW. Design and construction of a quadruple-resonance MAS NMR probe for investigation of extensively deuterated biomolecules. J Magn Reson 2017; 285:8-17. [PMID: 29059553 PMCID: PMC6317732 DOI: 10.1016/j.jmr.2017.10.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Revised: 10/03/2017] [Accepted: 10/06/2017] [Indexed: 05/22/2023]
Abstract
Extensive deuteration is frequently used in solid-state NMR studies of biomolecules because it dramatically reduces both homonuclear (1H-1H) and heteronuclear (1H-13C and 1H-15N) dipolar interactions. This approach greatly improves resolution, enables low-power rf decoupling, and facilitates 1H-detected experiments even in rigid solids at moderate MAS rates. However, the resolution enhancement is obtained at some cost due the reduced abundance of protons available for polarization transfer. Although deuterium is a useful spin-1 NMR nucleus, in typical experiments the deuterons are not directly utilized because the available probes are usually triple-tuned to 1H,13C and 15N. Here we describe a 1H/13C/2H/15N MAS ssNMR probe designed for solid-state NMR of extensively deuterated biomolecules. The probe utilizes coaxial coils, with a modified Alderman-Grant resonator for the 1H channel, and a multiply resonant solenoid for 13C/2H/15N. A coaxial tuning-tube design is used for all four channels in order to efficiently utilize the constrained physical space available inside the magnet bore. Isolation among the channels is likewise achieved using short, adjustable transmission line elements. We present benchmarks illustrating the tuning of each channel and isolation among them and the magnetic field profiles at each frequency of interest. Finally, representative NMR data are shown demonstrating the performance of both the detection and decoupling circuits.
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Affiliation(s)
- Kelsey A Collier
- Department of Physics & Astronomy, UC Irvine, Irvine, CA 92697-4575, United States
| | - Suvrajit Sengupta
- Department of Chemistry, UC Irvine, Irvine, CA 92697-2025, United States
| | | | - John E Kelly
- Department of Chemistry, UC Irvine, Irvine, CA 92697-2025, United States
| | - Jessica I Kelz
- Department of Chemistry, UC Irvine, Irvine, CA 92697-2025, United States
| | - Rachel W Martin
- Department of Chemistry, UC Irvine, Irvine, CA 92697-2025, United States; Department of Molecular Biology & Biochemistry, UC Irvine, Irvine, CA 92697-3900, United States.
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30
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Hayashi S, Jimura K. Spin diffusion and 1H spin-lattice relaxation in Cs 2(HSO 4)(H 2PO 4) containing a small amount of ammonium ions. Solid State Nucl Magn Reson 2017; 88:15-21. [PMID: 29126075 DOI: 10.1016/j.ssnmr.2017.10.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 10/23/2017] [Accepted: 10/24/2017] [Indexed: 06/07/2023]
Abstract
Inorganic solid acid salts with hydrogen bond networks frequently show very long spin-lattice relaxation times even for 1H because the hydrogen bonds suppress motions. In the present work, the 1H spin-lattice relaxation in Cs2(HSO4)(H2PO4) containing a small amount of ammonium ions were studied in detail by use of the effect of magic angle spinning (MAS) on the relaxation. The 1H spin-lattice relaxation times of the acid protons decrease with increase in the content of ammonium ions. Reorientation of the NH4 group fluctuates the dipole-dipole interaction and relaxes the ammonium protons as well as the acid protons. The 1H relaxation times of the acid protons are a little bit longer than those of the ammonium protons at the MAS rate of 8 kHz. The spinning at 50 kHz makes the relaxation times of the acid protons longer and those of the ammonium protons shorter. Spin diffusion between the acid and the ammonium protons averages partially the 1H relaxation of the acid and the ammonium protons at the MAS rate of 8 kHz. The spin diffusion is suppressed completely at the MAS rate of 50 kHz. Spin diffusion between the acid protons is not suppressed at the MAS rate of 50 kHz. The acid protons always show the same relaxation times. The intrinsic relaxation times not affected by spin diffusion are evaluated quantitatively for both the acid and the ammonium protons. Those values are independent of the ammonium content. Contribution of the spin diffusion between the acid and the ammonium protons to the relaxation is estimated quantitatively. Using those parameters, the effect of ammonium ions on the 1H spin-lattice relaxation can be predicted. The 1H spin-lattice relaxation is a sensitive tool to study the distribution of ammonium ions in solids.
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Affiliation(s)
- Shigenobu Hayashi
- Research Institute for Material and Chemical Measurement, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
| | - Keiko Jimura
- Research Institute for Material and Chemical Measurement, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan
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31
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Tošner Z, Purea A, Struppe JO, Wegner S, Engelke F, Glaser SJ, Reif B. Radiofrequency fields in MAS solid state NMR probes. J Magn Reson 2017; 284:20-32. [PMID: 28946058 DOI: 10.1016/j.jmr.2017.09.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 08/30/2017] [Accepted: 09/04/2017] [Indexed: 05/16/2023]
Abstract
We present a detailed analysis of the radiofrequency (RF) field over full volume of a rotor that is generated in a solenoid coil. On top of the usually considered static distribution of amplitudes along the coil axis we describe dynamic radial RF inhomogeneities induced by sample rotation. During magic angle spinning (MAS), the mechanical rotation of the sample about the magic angle, a spin packet travels through areas of different RF fields and experiences periodical modulations of both the RF amplitude and the phase. These modulations become particularly severe at the end regions of the coil where the relative RF amplitude varies up to ±25% and the RF phase changes within ±30°. Using extensive numerical simulations we demonstrate effects of RF inhomogeneity on pulse calibration and for the ramped CP experiment performed at a wide range of MAS rates. In addition, we review various methods to map RF fields using a B0 gradient along the sample (rotor axis) for imaging purposes. Under such a gradient, a nutation experiment provides directly the RF amplitude distribution, a cross polarization experiment images the correlation of the RF fields on the two channels according to the Hartmann-Hahn matching condition, while a spin-lock experiment allows to calibrate the RF amplitude employing the rotary resonance recoupling condition. Knowledge of the RF field distribution in a coil provides key to understand its effects on performance of a pulse sequence at the spectrometer and enables to set robustness requirements in the experimental design.
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Affiliation(s)
- Zdeněk Tošner
- Munich Center for Integrated Protein Science (CIPS-M) at Department of Chemistry, Technical University of Munich, Lichtenbergstr. 4, 85747 Garching, Germany; Department of Chemistry, Technical University of Munich, Lichtenbergstr. 4, 85747 Garching, Germany; Department of Chemistry, Faculty of Science, Charles University, Hlavova 8, 12842 Prague 2, Czech Republic.
| | - Armin Purea
- Bruker BioSpin, Silberstreifen 4, 76287 Rheinstetten, Germany
| | | | | | - Frank Engelke
- Bruker BioSpin, Silberstreifen 4, 76287 Rheinstetten, Germany
| | - Steffen J Glaser
- Department of Chemistry, Technical University of Munich, Lichtenbergstr. 4, 85747 Garching, Germany
| | - Bernd Reif
- Munich Center for Integrated Protein Science (CIPS-M) at Department of Chemistry, Technical University of Munich, Lichtenbergstr. 4, 85747 Garching, Germany; Department of Chemistry, Technical University of Munich, Lichtenbergstr. 4, 85747 Garching, Germany; Helmholtz-Zentrum München (HMGU), Deutsches Forschungszentrum für Gesundheit und Umwelt, Ingolstädter Landstr. 1, 85764 Neuherberg, Germany
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32
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Hayashi S, Jimura K. Detailed mechanisms of 1H spin-lattice relaxation in ammonium dihydrogen phosphate confirmed by magic angle spinning. Solid State Nucl Magn Reson 2017; 87:24-28. [PMID: 28728051 DOI: 10.1016/j.ssnmr.2017.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 07/04/2017] [Accepted: 07/05/2017] [Indexed: 06/07/2023]
Abstract
Mechanisms of the 1H spin-lattice relaxation in NH4H2PO4 were studied in detail by use of the effect of magic angle spinning on the relaxation. The acid and the ammonium protons have different relaxation times at the spinning rates higher than 10 kHz due to suppression of spin diffusion between the two kinds of protons. The intrinsic relaxation times not affected by the spin diffusion and the spin-diffusion assisted relaxation times were evaluated separately, taking into consideration temperature dependence. Both mechanisms contribute to the 1H relaxation of the acid protons comparatively. The spin-diffusion assisted relaxation mechanism was suppressed to the level lower than the experimental errors at the spinning rate of 30 kHz.
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Affiliation(s)
- Shigenobu Hayashi
- Research Institute for Material and Chemical Measurement, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8565, Japan.
| | - Keiko Jimura
- Research Institute for Material and Chemical Measurement, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8565, Japan
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33
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Gupta R, Huang W, Francesconi LC, Polenova T. Effect of positional isomerism and vanadium substitution on 51V magic angle spinning NMR Spectra Of Wells-Dawson polyoxotungstates. Solid State Nucl Magn Reson 2017; 84:28-33. [PMID: 27998683 PMCID: PMC5466850 DOI: 10.1016/j.ssnmr.2016.12.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2016] [Revised: 12/02/2016] [Accepted: 12/04/2016] [Indexed: 06/06/2023]
Abstract
We examined the positional isomerism and vanadium substitution on the 51V magic angle spinning NMR spectra of potassium salts of vanadium-substituted polyoxotungstates of the Wells-Dawson series. NMR parameters of this class of catalytically active polyoxotungstates effect of are reported. Multiple species, indicative of differences in the local environment at the substitution sites, are observed in solid-state NMR spectra of the di- and tri- substituted complexes in contrast to solution NMR spectra, where single average chemical shift was observed. The quadrupolar and chemical shift anisotropy parameters depend strongly on the position and the degree of the vanadium substitution into the oxoanion core establishing 51V SATRAS NMR spectroscopy as a sensitive probe of the local electronic environment in these catalytically active solids.
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Affiliation(s)
- Rupal Gupta
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA
| | - Wenlin Huang
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA
| | - Lynn C Francesconi
- Department of Chemistry, City University of New York, Hunter College, 695 Park Avenue, New York 10021, USA; Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York 10016, USA.
| | - Tatyana Polenova
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA.
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34
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Lee D, Chaudhari SR, De Paëpe G. Solvent signal suppression for high-resolution MAS-DNP. J Magn Reson 2017; 278:60-66. [PMID: 28365491 DOI: 10.1016/j.jmr.2017.03.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 03/13/2017] [Accepted: 03/20/2017] [Indexed: 06/07/2023]
Abstract
Dynamic nuclear polarization (DNP) has become a powerful tool to substantially increase the sensitivity of high-field magic angle spinning (MAS) solid-state NMR experiments. The addition of dissolved hyperpolarizing agents usually results in the presence of solvent signals that can overlap and obscure those of interest from the analyte. Here, two methods are proposed to suppress DNP solvent signals: a Forced Echo Dephasing experiment (FEDex) and TRAnsfer of Populations in DOuble Resonance Echo Dephasing (TRAPDORED) NMR. These methods reintroduce a heteronuclear dipolar interaction that is specific to the solvent, thereby forcing a dephasing of recoupled solvent spins and leaving acquired NMR spectra free of associated resonance overlap with the analyte. The potency of these methods is demonstrated on sample types common to MAS-DNP experiments, namely a frozen solution (of l-proline) and a powdered solid (progesterone), both containing deuterated glycerol as a DNP solvent. The proposed methods are efficient, simple to implement, compatible with other NMR experiments, and extendable past spectral editing for just DNP solvents. The sensitivity gains from MAS-DNP in conjunction with FEDex or TRAPDORED then permits rapid and uninterrupted sample analysis.
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Affiliation(s)
- Daniel Lee
- Univ. Grenoble Alpes, INAC, F-38000 Grenoble, France; CEA, INAC, F-38000 Grenoble, France
| | - Sachin R Chaudhari
- Univ. Grenoble Alpes, INAC, F-38000 Grenoble, France; CEA, INAC, F-38000 Grenoble, France
| | - Gaël De Paëpe
- Univ. Grenoble Alpes, INAC, F-38000 Grenoble, France; CEA, INAC, F-38000 Grenoble, France.
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35
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Yao Y, Dutta SK, Park SH, Rai R, Fujimoto LM, Bobkov AA, Opella SJ, Marassi FM. High resolution solid-state NMR spectroscopy of the Yersinia pestis outer membrane protein Ail in lipid membranes. J Biomol NMR 2017; 67:179-190. [PMID: 28239773 PMCID: PMC5490241 DOI: 10.1007/s10858-017-0094-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 02/08/2017] [Indexed: 06/06/2023]
Abstract
The outer membrane protein Ail (Adhesion invasion locus) is one of the most abundant proteins on the cell surface of Yersinia pestis during human infection. Its functions are expressed through interactions with a variety of human host proteins, and are essential for microbial virulence. Structures of Ail have been determined by X-ray diffraction and solution NMR spectroscopy, but those samples contained detergents that interfere with functionality, thus, precluding analysis of the structural basis for Ail's biological activity. Here, we demonstrate that high-resolution solid-state NMR spectra can be obtained from samples of Ail in detergent-free phospholipid liposomes, prepared with a lipid to protein molar ratio of 100. The spectra, obtained with 13C or 1H detection, have very narrow line widths (0.40-0.60 ppm for 13C, 0.11-0.15 ppm for 1H, and 0.46-0.64 ppm for 15N) that are consistent with a high level of sample homogeneity. The spectra enable resonance assignments to be obtained for N, CO, CA and CB atomic sites from 75 out of 156 residues in the sequence of Ail, including 80% of the transmembrane region. The 1H-detected solid-state NMR 1H/15N correlation spectra obtained for Ail in liposomes compare very favorably with the solution NMR 1H/15N TROSY spectra obtained for Ail in nanodiscs prepared with a similar lipid to protein molar ratio. These results set the stage for studies of the molecular basis of the functional interactions of Ail with its protein partners from human host cells, as well as the development of drugs targeting Ail.
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Affiliation(s)
- Yong Yao
- Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Samit Kumar Dutta
- Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Sang Ho Park
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0307, USA
| | - Ratan Rai
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0307, USA
| | - L Miya Fujimoto
- Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Andrey A Bobkov
- Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Stanley J Opella
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0307, USA
| | - Francesca M Marassi
- Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, La Jolla, CA, 92037, USA.
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36
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Guo C, Hou G, Lu X, Polenova T. Mapping protein-protein interactions by double-REDOR-filtered magic angle spinning NMR spectroscopy. J Biomol NMR 2017; 67:95-108. [PMID: 28120201 PMCID: PMC6258002 DOI: 10.1007/s10858-016-0086-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 12/25/2016] [Indexed: 05/03/2023]
Abstract
REDOR-based experiments with simultaneous 1H-13C and 1H-15N dipolar dephasing are explored for investigating intermolecular protein-protein interfaces in complexes formed by a U-13C,15N-labeled protein and its natural abundance binding partner. The application of a double-REDOR filter (dREDOR) results in a complete dephasing of proton magnetization in the U-13C,15N-enriched molecule while the proton magnetization of the unlabeled binding partner is not dephased. This retained proton magnetization is then transferred across the intermolecular interface by 1H-13C or 1H-15N cross polarization, permitting to establish the residues of the U-13C,15N-labeled protein, which constitute the binding interface. To assign the interface residues, this dREDOR-CPMAS element is incorporated as a building block into 13C-13C correlation experiments. We established the validity of this approach on U-13C,15N-histidine and on a structurally characterized complex of dynactin's U-13C,15N-CAP-Gly domain with end-binding protein 1 (EB1). The approach introduced here is broadly applicable to the analysis of intermolecular interfaces when one of the binding partners in a complex cannot be isotopically labeled.
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Affiliation(s)
- Changmiao Guo
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
| | - Guangjin Hou
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA.
| | - Xingyu Lu
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
| | - Tatyana Polenova
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA.
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37
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Khaneja N, Kumar A. Recoupling pulse sequences with constant phase increments. J Magn Reson 2016; 271:75-82. [PMID: 27569693 DOI: 10.1016/j.jmr.2016.08.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Revised: 08/15/2016] [Accepted: 08/20/2016] [Indexed: 06/06/2023]
Abstract
The paper studies a family of recoupling pulse sequences in magic angle spinning (MAS) solid state NMR, that are characterized by constant phase increments at regular intervals. These pulse sequences can be employed for both homonuclear and heteronuclear recoupling experiments and are robust to dispersion in chemical shifts and rf-inhomogeneity. The homonuclear pulse sequence consists of a building block [Formula: see text] , where ϕ(p)=p(n-1)πn, where n is number of blocks in a rotor period and p=0,1,2,…. The pulse sequence repeats itself every rotor period when n is odd and every two rotor period when n is even. The heteronuclear recoupling pulse sequence consists of a building block [Formula: see text] and [Formula: see text] on channel I and S, where ϕ1(p)=p(2n-3)π2n,ϕ2(p)=p(2n-1)π2n and n is number of blocks in a rotor period. The recoupling pulse sequences mix the z magnetization. Experimental quantification of this method is shown for (13)Cα-(13)CO, homonuclear recoupling in a sample of Glycine and (15)N-(13)Cα, heteronuclear recoupling in Alanine. Application of this method is demonstrated on a sample of tripeptide N-formyl-[U-(13)C,(15)N]- Met-Leu-Phe-OH (MLF).
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Affiliation(s)
- Navin Khaneja
- Department of Electrical Engineering, IIT Bombay, Powai 400076, India.
| | - Ashutosh Kumar
- Department of Biosciences and Bioengineering, IIT Bombay, Powai 400076, India
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38
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Lindh EL, Stilbs P, Furó I. Site-resolved (2)H relaxation experiments in solid materials by global line-shape analysis of MAS NMR spectra. J Magn Reson 2016; 268:18-24. [PMID: 27152833 DOI: 10.1016/j.jmr.2016.04.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 04/20/2016] [Accepted: 04/25/2016] [Indexed: 06/05/2023]
Abstract
We investigate a way one can achieve good spectral resolution in (2)H MAS NMR experiments. The goal is to be able to distinguish between and study sites in various deuterated materials with small chemical shift dispersion. We show that the (2)H MAS NMR spectra recorded during a spin-relaxation experiment are amenable to spectral decomposition because of the different evolution of spectral components during the relaxation delay. We verify that the results are robust by global least-square fitting of the spectral series both under the assumption of specific line shapes and without such assumptions (COmponent-REsolved spectroscopy, CORE). In addition, we investigate the reliability of the developed protocol by analyzing spectra simulated with different combinations of spectral parameters. The performance is demonstrated in a model material of deuterated poly(methacrylic acid) that contains two (2)H spin populations with similar chemical shifts but different quadrupole splittings. In (2)H-exchanged cellulose containing two (2)H spin populations with very similar chemical shifts and quadrupole splittings, the method provides new site-selective information about the molecular dynamics.
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Affiliation(s)
- E L Lindh
- Division of Applied Physical Chemistry, Department of Chemistry, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden; Wallenberg Wood Science Center, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden; Innventia AB, Box 5604, SE-114 86 Stockholm, Sweden
| | - P Stilbs
- Division of Applied Physical Chemistry, Department of Chemistry, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden
| | - I Furó
- Division of Applied Physical Chemistry, Department of Chemistry, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden.
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39
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Sarkar R, Mainz A, Busi B, Barbet-Massin E, Kranz M, Hofmann T, Reif B. Immobilization of soluble protein complexes in MAS solid-state NMR: Sedimentation versus viscosity. Solid State Nucl Magn Reson 2016; 76-77:7-14. [PMID: 27017576 DOI: 10.1016/j.ssnmr.2016.03.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 03/10/2016] [Accepted: 03/11/2016] [Indexed: 05/12/2023]
Abstract
In recent years, MAS solid-state NMR has emerged as a technique for the investigation of soluble protein complexes. It was found that high molecular weight complexes do not need to be crystallized in order to obtain an immobilized sample for solid-state NMR investigations. Sedimentation induced by sample rotation impairs rotational diffusion of proteins and enables efficient dipolar coupling based cross polarization transfers. In addition, viscosity contributes to the immobilization of the molecules in the sample. Natural Deep Eutectic Solvents (NADES) have very high viscosities, and can replace water in living organisms. We observe a considerable amount of cross polarization transfers for NADES solvents, even though their molecular weight is too low to yield significant sedimentation. We discuss how viscosity and sedimentation both affect the quality of the obtained experimental spectra. The FROSTY/sedNMR approach holds the potential to study large protein complexes, which are otherwise not amenable for a structural characterization using NMR. We show that using this method, backbone assignments of the symmetric proteasome activator complex (1.1MDa), and high quality correlation spectra of non-symmetric protein complexes such as the prokaryotic ribosome 50S large subunit binding to trigger factor (1.4MDa) are obtained.
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Affiliation(s)
- Riddhiman Sarkar
- Munich Center for Integrated Protein Science (CIPSM) at Department of Chemie, Technische Universität München (TUM), Lichtenbergstr. 4, D-85747 Garching, Germany; Helmholtz-Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt (HMGU), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
| | - Andi Mainz
- Munich Center for Integrated Protein Science (CIPSM) at Department of Chemie, Technische Universität München (TUM), Lichtenbergstr. 4, D-85747 Garching, Germany; Helmholtz-Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt (HMGU), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany; Technische Universität Berlin, Fakultät II Mathematik und Naturwissenschaften, Institut für Chemie/OC/Biologische Chemie, Müller-Breslau-Straße 10, 10623 Berlin, Germany
| | - Baptiste Busi
- Munich Center for Integrated Protein Science (CIPSM) at Department of Chemie, Technische Universität München (TUM), Lichtenbergstr. 4, D-85747 Garching, Germany; Helmholtz-Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt (HMGU), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
| | - Emeline Barbet-Massin
- Munich Center for Integrated Protein Science (CIPSM) at Department of Chemie, Technische Universität München (TUM), Lichtenbergstr. 4, D-85747 Garching, Germany; Helmholtz-Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt (HMGU), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
| | - Maximilian Kranz
- Chair of Food Chemistry and Molecular Sensory Science, Technische Universitat¨ Mu¨nchen, Lise-Meitner-Strasse 34, 85354 Freising, Germany
| | - Thomas Hofmann
- Chair of Food Chemistry and Molecular Sensory Science, Technische Universitat¨ Mu¨nchen, Lise-Meitner-Strasse 34, 85354 Freising, Germany
| | - Bernd Reif
- Munich Center for Integrated Protein Science (CIPSM) at Department of Chemie, Technische Universität München (TUM), Lichtenbergstr. 4, D-85747 Garching, Germany; Helmholtz-Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt (HMGU), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany.
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40
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Gopinath T, Veglia G. Multiple acquisitions via sequential transfer of orphan spin polarization (MAeSTOSO): How far can we push residual spin polarization in solid-state NMR? J Magn Reson 2016; 267:1-8. [PMID: 27039168 PMCID: PMC4862926 DOI: 10.1016/j.jmr.2016.03.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Revised: 02/22/2016] [Accepted: 03/07/2016] [Indexed: 05/05/2023]
Abstract
Conventional multidimensional magic angle spinning (MAS) solid-state NMR (ssNMR) experiments detect the signal arising from the decay of a single coherence transfer pathway (FID), resulting in one spectrum per acquisition time. Recently, we introduced two new strategies, namely DUMAS (DUal acquisition Magic Angle Spinning) and MEIOSIS (Multiple ExperIments via Orphan SpIn operatorS), that enable the simultaneous acquisitions of multidimensional ssNMR experiments using multiple coherence transfer pathways. Here, we combined the main elements of DUMAS and MEIOSIS to harness both orphan spin operators and residual polarization and increase the number of simultaneous acquisitions. We show that it is possible to acquire up to eight two-dimensional experiments using four acquisition periods per each scan. This new suite of pulse sequences, called MAeSTOSO for Multiple Acquisitions via Sequential Transfer of Orphan Spin pOlarization, relies on residual polarization of both (13)C and (15)N pathways and combines low- and high-sensitivity experiments into a single pulse sequence using one receiver and commercial ssNMR probes. The acquisition of multiple experiments does not affect the sensitivity of the main experiment; rather it recovers the lost coherences that are discarded, resulting in a significant gain in experimental time. Both merits and limitations of this approach are discussed.
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Affiliation(s)
- T Gopinath
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, United States
| | - Gianluigi Veglia
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, United States; Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, United States.
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41
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Hisao GS, Harland MA, Brown RA, Berthold DA, Wilson TE, Rienstra CM. An efficient method and device for transfer of semisolid materials into solid-state NMR spectroscopy rotors. J Magn Reson 2016; 265:172-6. [PMID: 26905816 PMCID: PMC4818695 DOI: 10.1016/j.jmr.2016.01.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 01/17/2016] [Indexed: 05/23/2023]
Abstract
The study of mass-limited biological samples by magic angle spinning (MAS) solid-state NMR spectroscopy critically relies upon the high-yield transfer of material from a biological preparation into the MAS rotor. This issue is particularly important for maintaining biological activity and hydration of semi-solid samples such as membrane proteins in lipid bilayers, pharmaceutical formulations, microcrystalline proteins and protein fibrils. Here we present protocols and designs for rotor-packing devices specifically suited for packing hydrated samples into Pencil-style 1.6 mm, 3.2 mm standard, and 3.2 mm limited speed MAS rotors. The devices are modular and therefore readily adaptable to other rotor and/or ultracentrifugation tube geometries.
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Affiliation(s)
- Grant S Hisao
- University of Illinois at Urbana-Champaign, Department of Chemistry, 600 South Mathews Avenue, Urbana, IL 61801, USA.
| | - Michael A Harland
- University of Illinois at Urbana-Champaign, School of Chemical Sciences Machine Shop, 505 South Matthews Ave., Urbana, IL 61801, USA.
| | - Robert A Brown
- University of Illinois at Urbana-Champaign, School of Chemical Sciences Machine Shop, 505 South Matthews Ave., Urbana, IL 61801, USA
| | - Deborah A Berthold
- University of Illinois at Urbana-Champaign, Department of Chemistry, 600 South Mathews Avenue, Urbana, IL 61801, USA.
| | - Thomas E Wilson
- University of Illinois at Urbana-Champaign, School of Chemical Sciences Machine Shop, 505 South Matthews Ave., Urbana, IL 61801, USA.
| | - Chad M Rienstra
- University of Illinois at Urbana-Champaign, Department of Chemistry, 600 South Mathews Avenue, Urbana, IL 61801, USA; University of Illinois at Urbana-Champaign, Department of Biochemistry, Center for Biophysics and Quantitative Biology, 600 South Mathews Avenue, Urbana, IL 61801, USA.
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42
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Lee D, Bouleau E, Saint-Bonnet P, Hediger S, De Paëpe G. Ultra-low temperature MAS-DNP. J Magn Reson 2016; 264:116-124. [PMID: 26920837 DOI: 10.1016/j.jmr.2015.12.010] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2015] [Revised: 12/15/2015] [Accepted: 12/16/2015] [Indexed: 05/05/2023]
Abstract
Since the infancy of NMR spectroscopy, sensitivity and resolution have been the limiting factors of the technique. Regular essential developments on this front have led to the widely applicable, versatile, and powerful spectroscopy that we know today. However, the Holy Grail of ultimate sensitivity and resolution is not yet reached, and technical improvements are still ongoing. Hence, high-field dynamic nuclear polarization (DNP) making use of high-frequency, high-power microwave irradiation of electron spins has become very promising in combination with magic angle sample spinning (MAS) solid-state NMR experiments. This is because it leads to a transfer of the much larger polarization of these electron spins under suitable irradiation to surrounding nuclei, greatly increasing NMR sensitivity. Currently, this boom in MAS-DNP is mainly performed at minimum sample temperatures of about 100K, using cold nitrogen gas to pneumatically spin and cool the sample. This Perspective deals with the desire to improve further the sensitivity and resolution by providing "ultra"-low temperatures for MAS-DNP, using cryogenic helium gas. Different designs on how this technological challenge has been overcome are described. It is shown that stable and fast spinning can be attained for sample temperatures down to 30K using a large cryostat developed in our laboratory. Using this cryostat to cool a closed-loop of helium gas brings the additional advantage of sample spinning frequencies that can greatly surpass those achievable with nitrogen gas, due to the differing fluidic properties of these two gases. It is shown that using ultra-low temperatures for MAS-DNP results in substantial experimental sensitivity enhancements and according time-savings. Access to this temperature range is demonstrated to be both viable and highly pertinent.
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Affiliation(s)
- Daniel Lee
- Univ. Grenoble Alpes, INAC, F-38000 Grenoble, France; CEA, INAC, F-38000 Grenoble, France
| | - Eric Bouleau
- Univ. Grenoble Alpes, INAC, F-38000 Grenoble, France; CEA, INAC, F-38000 Grenoble, France
| | - Pierre Saint-Bonnet
- Univ. Grenoble Alpes, INAC, F-38000 Grenoble, France; CEA, INAC, F-38000 Grenoble, France
| | - Sabine Hediger
- Univ. Grenoble Alpes, INAC, F-38000 Grenoble, France; CEA, INAC, F-38000 Grenoble, France; CNRS, SCIB, F-38000 Grenoble, France
| | - Gaël De Paëpe
- Univ. Grenoble Alpes, INAC, F-38000 Grenoble, France; CEA, INAC, F-38000 Grenoble, France
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43
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Das BB, Opella SJ. Simultaneous cross polarization to (13)C and (15)N with (1)H detection at 60kHz MAS solid-state NMR. J Magn Reson 2016; 262:20-26. [PMID: 26705905 PMCID: PMC4716881 DOI: 10.1016/j.jmr.2015.12.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 11/30/2015] [Accepted: 12/02/2015] [Indexed: 05/05/2023]
Abstract
We describe high resolution MAS solid-state NMR experiments that utilize (1)H detection with 60kHz magic angle spinning; simultaneous cross-polarization from (1)H to (15)N and (13)C nuclei; bidirectional cross-polarization between (13)C and (15)N nuclei; detection of both amide nitrogen and aliphatic carbon (1)H; and measurement of both (13)C and (15)N chemical shifts through multi-dimensional correlation experiments. Three-dimensional experiments correlate amide (1)H and alpha (1)H selectively with (13)C or (15)N nuclei in a polypeptide chain. Two separate three-dimensional spectra correlating (1)Hα/(13)Cα/(1)H(N) and (1)H(N)/(15)N/(1)Hα are recorded simultaneously in a single experiment, demonstrating that a twofold savings in experimental time is potentially achievable. Spectral editing using bidirectional coherence transfer pathways enables simultaneous magnetization transfers between (15)N, (13)Cα(()(i)()) and (13)C'(()(i)(-1)), facilitating intra- and inter-residue correlations for sequential resonance assignment. Non-uniform sampling is integrated into the experiments, further reducing the length of experimental time.
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Affiliation(s)
- Bibhuti B Das
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA
| | - Stanley J Opella
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA.
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44
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Hoff DEM, Albert BJ, Saliba EP, Scott FJ, Choi EJ, Mardini M, Barnes AB. Frequency swept microwaves for hyperfine decoupling and time domain dynamic nuclear polarization. Solid State Nucl Magn Reson 2015; 72:79-89. [PMID: 26482131 PMCID: PMC4762658 DOI: 10.1016/j.ssnmr.2015.10.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2015] [Revised: 09/30/2015] [Accepted: 10/01/2015] [Indexed: 05/05/2023]
Abstract
Hyperfine decoupling and pulsed dynamic nuclear polarization (DNP) are promising techniques to improve high field DNP NMR. We explore experimental and theoretical considerations to implement them with magic angle spinning (MAS). Microwave field simulations using the high frequency structural simulator (HFSS) software suite are performed to characterize the inhomogeneous phase independent microwave field throughout a 198GHz MAS DNP probe. Our calculations show that a microwave power input of 17W is required to generate an average EPR nutation frequency of 0.84MHz. We also present a detailed calculation of microwave heating from the HFSS parameters and find that 7.1% of the incident microwave power contributes to dielectric sample heating. Voltage tunable gyrotron oscillators are proposed as a class of frequency agile microwave sources to generate microwave frequency sweeps required for the frequency modulated cross effect, electron spin inversions, and hyperfine decoupling. Electron spin inversions of stable organic radicals are simulated with SPINEVOLUTION using the inhomogeneous microwave fields calculated by HFSS. We calculate an electron spin inversion efficiency of 56% at a spinning frequency of 5kHz. Finally, we demonstrate gyrotron acceleration potentials required to generate swept microwave frequency profiles for the frequency modulated cross effect and electron spin inversions.
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Affiliation(s)
- Daniel E M Hoff
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130, USA
| | - Brice J Albert
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130, USA
| | - Edward P Saliba
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130, USA
| | - Faith J Scott
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130, USA
| | - Eric J Choi
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130, USA
| | - Michael Mardini
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130, USA
| | - Alexander B Barnes
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130, USA.
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45
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Gupta R, Hou G, Polenova T, Vega AJ. RF inhomogeneity and how it controls CPMAS. Solid State Nucl Magn Reson 2015; 72:17-26. [PMID: 26422256 PMCID: PMC4674349 DOI: 10.1016/j.ssnmr.2015.09.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Revised: 09/04/2015] [Accepted: 09/04/2015] [Indexed: 05/09/2023]
Abstract
In this report we discuss the effect of radiofrequency field (RF) inhomogeneity on cross-polarization (CP) under magic-angle spinning (MAS) by reviewing the dependence of the CP-detected signal intensity as a function of the position in the sample space. We introduce a power-function model to quantify the position-dependent RF-amplitude profile. The applicability of this model is experimentally verified by nutation spectra obtained by direct signal detection, as well as by CPMAS signal detection, in two commercial MAS probes with different degrees of RF inhomogeneity. A conclusion is that substantial sections of a totally filled rotor, even in a probe with rather good homogeneity, do not contribute at all to the detected spectra. The consequence is that in CPMAS-based recoupling experiments, such as the CP-with-variable-contact-time (CPVC), spatial selectivity of the Hartmann-Hahn matching condition overcomes complications that could be caused by RF inhomogeneity permitting determination of accurate spectral parameters even in cases with high inhomogeneity.
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Affiliation(s)
- Rupal Gupta
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA
| | - Guangjin Hou
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA
| | - Tatyana Polenova
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA
| | - Alexander J Vega
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA.
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46
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Nimerovsky E, Haimovich A, Goldbourt A. An optimal double-magic flip angle for performing the distance measurement REDOR experiment on a spin S=1. Solid State Nucl Magn Reson 2015; 72:127-131. [PMID: 26358981 DOI: 10.1016/j.ssnmr.2015.08.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2015] [Revised: 08/02/2015] [Accepted: 08/19/2015] [Indexed: 06/05/2023]
Abstract
Distance measurements between a half-spin and a quadrupolar S=1 spin having a small quadrupolar coupling constant can be performed using the rotational echo double resonance (REDOR) experiment. We derived an analytical expression for the probability of transitions between energy levels resulting from the application of an arbitrary pulse flip angle to the quadrupolar spin and consequently minimized the probability that populations of individual levels do not undergo a spin transition during the pulse. As a result we discovered that if the flip angle of the quadrupolar spin pulse is 109.47°, the maximal recoupling values are the largest possible and the signal reaches a maximum value of 8/9, larger than in the use of either a 90° pulse or a 180° pulse. In addition, the slope of the initial decay is higher than that of the 90° pulse. The recoupling signal can be modeled by an exact analytical formula in the ideal case and simulations show that the advantage of the 109.47° pulse is preserved when the quadrupolar coupling constant CQ has a finite value typical of (2)H and (6)Li spins (up to CQ~200kHz). Experimental results on two spin pairs, (2)H-(13)C and (6)Li-(13)C, demonstrate the validity and accuracy of this method.
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Affiliation(s)
- E Nimerovsky
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Ramat Aviv 69978, Tel Aviv, Israel
| | - A Haimovich
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Ramat Aviv 69978, Tel Aviv, Israel
| | - A Goldbourt
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Ramat Aviv 69978, Tel Aviv, Israel.
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Wilhelm D, Purea A, Engelke F. Fluid flow dynamics in MAS systems. J Magn Reson 2015; 257:51-63. [PMID: 26073599 DOI: 10.1016/j.jmr.2015.05.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Revised: 05/15/2015] [Accepted: 05/18/2015] [Indexed: 06/04/2023]
Abstract
The turbine system and the radial bearing of a high performance magic angle spinning (MAS) probe with 1.3mm-rotor diameter has been analyzed for spinning rates up to 67kHz. We focused mainly on the fluid flow properties of the MAS system. Therefore, computational fluid dynamics (CFD) simulations and fluid measurements of the turbine and the radial bearings have been performed. CFD simulation and measurement results of the 1.3mm-MAS rotor system show relatively low efficiency (about 25%) compared to standard turbo machines outside the realm of MAS. However, in particular, MAS turbines are mainly optimized for speed and stability instead of efficiency. We have compared MAS systems for rotor diameter of 1.3-7mm converted to dimensionless values with classical turbomachinery systems showing that the operation parameters (rotor diameter, inlet mass flow, spinning rate) are in the favorable range. This dimensionless analysis also supports radial turbines for low speed MAS probes and diagonal turbines for high speed MAS probes. Consequently, a change from Pelton type MAS turbines to diagonal turbines might be worth considering for high speed applications. CFD simulations of the radial bearings have been compared with basic theoretical values proposing considerably smaller frictional loss values. The discrepancies might be due to the simple linear flow profile employed for the theoretical model. Frictional losses generated inside the radial bearings result in undesired heat-up of the rotor. The rotor surface temperature distribution computed by CFD simulations show a large temperature gradient over the rotor.
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Affiliation(s)
- Dirk Wilhelm
- Zurich University of Applied Sciences, Institute of Applied Mathematics and Physics, Techikumstrasse 9, 8400 Winterthur, Switzerland.
| | - Armin Purea
- Bruker Biospin GmbH, Am Silberstreifen 4, 76287 Rheinstetten, Germany
| | - Frank Engelke
- Bruker Biospin GmbH, Am Silberstreifen 4, 76287 Rheinstetten, Germany
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Haimovich A, Goldbourt A. Characterization of lithium coordination sites with magic-angle spinning NMR. J Magn Reson 2015; 254:131-138. [PMID: 25899290 DOI: 10.1016/j.jmr.2015.02.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Revised: 01/28/2015] [Accepted: 02/07/2015] [Indexed: 06/04/2023]
Abstract
Lithium, in the form of lithium carbonate, is one of the most common drugs for bipolar disorder. Lithium is also considered to have an effect on many other cellular processes hence it possesses additional therapeutic as well as side effects. In order to quantitatively characterize the binding mode of lithium, it is required to identify the interacting species and measure their distances from the metal center. Here we use magic-angle spinning (MAS) solid-state NMR to study the binding site of lithium in complex with glycine and water (LiGlyW). Such a compound is a good enzyme mimetic since lithium is four-coordinated to one water molecule and three carboxylic groups. Distance measurements to carbons are performed using a 2D transferred echo double resonance (TEDOR) MAS solid-state NMR experiment, and water binding is probed by heteronuclear high-resolution proton-lithium and proton-carbon correlation (wPMLG-HETCOR) experiments. Both HETCOR experiments separate the main complex from impurities and non-specifically bound lithium species, demonstrating the sensitivity of the method to probe the species in the binding site. Optimizations of the TEDOR pulse scheme in the case of a quadrupolar nucleus with a small quadrupole coupling constant show that it is most efficient when pulses are positioned on the spin-1/2 (carbon-13) nucleus. Since the intensity of the TEDOR signal is not normalized, careful data analysis that considers both intensity and dipolar oscillations has to be performed. Nevertheless we show that accurate distances can be extracted for both carbons of the bound glycine and that these distances are consistent with the X-ray data and with lithium in a tetrahedral environment. The lithium environment in the complex is very similar to the binding site in inositol monophosphatase, an enzyme associated with bipolar disorder and the putative target for lithium therapy. A 2D TEDOR experiment applied to the bacterial SuhB gene product of this enzyme was designed to probe direct correlations between lithium, the enzyme inhibitor, and the closest carboxyl carbons of the binding site. At this point, the chemical shift of the bound carboxyl groups in this 29 kDa enzyme could be determined.
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Affiliation(s)
- A Haimovich
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Ramat Aviv 69978, Tel Aviv, Israel
| | - A Goldbourt
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Ramat Aviv 69978, Tel Aviv, Israel.
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Abstract
The native environment for a membrane protein is a phospholipid bilayer. Because the protein is immobilized on NMR timescales by the interactions within a bilayer membrane, solid-state NMR methods are essential to obtain high-resolution spectra. Approaches have been developed for both unoriented and oriented samples, however, they all rest on the foundation of the most fundamental aspects of solid-state NMR, and the chemical shift and homo- and hetero-nuclear dipole-dipole interactions. Solid-state NMR has advanced sufficiently to enable the structures of membrane proteins to be determined under near-native conditions in phospholipid bilayers.
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Affiliation(s)
- Stanley J Opella
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA.
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Lee D, Hediger S, De Paëpe G. Is solid-state NMR enhanced by dynamic nuclear polarization? Solid State Nucl Magn Reson 2015; 66-67:6-20. [PMID: 25779337 DOI: 10.1016/j.ssnmr.2015.01.003] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 01/27/2015] [Accepted: 01/28/2015] [Indexed: 05/03/2023]
Abstract
The recent trend of high-field (~5-20 T), low-temperature (~100 K) ssNMR combined with dynamic nuclear polarization (DNP) under magic angle spinning (MAS) conditions is analyzed. A brief overview of the current theory of hyperpolarization for so-called MAS-DNP experiments is given, along with various reasons why the DNP-enhancement, the ratio of the NMR signal intensities obtained in the presence and absence of microwave irradiation suitable for hyperpolarization, should not be used alone to gauge the value of performing MAS-DNP experiments relative to conventional ssNMR. This is demonstrated through a dissection of the current conditions required for MAS-DNP with particular attention to resulting absolute sensitivities and spectral resolution. Consequently, sample preparation methods specifically avoiding the surplus of glass-forming solvents so as to improve the absolute sensitivity and resolution are discussed, as are samples that are intrinsically pertinent for MAS-DNP studies (high surface area, amorphous, and porous). Owing to their pertinence, examples of recent applications on these types of samples where chemically-relevant information has been obtained that would have been impossible without the sensitivity increases bestowed by MAS-DNP are also detailed. Additionally, a promising further implementation for MAS-DNP is exampled, whereby the sensitivity improvements shown for (correlation) spectroscopy of nuclei at low natural isotopic abundance, facilitate internuclear distance measurements, especially for long distances (absence of dipolar truncation). Finally, we give some speculative perspectives for MAS-DNP.
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Affiliation(s)
- Daniel Lee
- Univ. Grenoble Alpes, INAC, SCIB, F-38000 Grenoble, France; CEA, INAC, SCIB, F-38000 Grenoble, France.
| | - Sabine Hediger
- Univ. Grenoble Alpes, INAC, SCIB, F-38000 Grenoble, France; CEA, INAC, SCIB, F-38000 Grenoble, France; CNRS, SCIB, F-38000 Grenoble, France
| | - Gaël De Paëpe
- Univ. Grenoble Alpes, INAC, SCIB, F-38000 Grenoble, France; CEA, INAC, SCIB, F-38000 Grenoble, France
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