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Wu D, Koscic A, Schneider S, Dubini RCA, Rodriguez Camargo DC, Schneider S, Rovó P. Unveiling the Dynamic Self-Assembly of a Recombinant Dragline-Silk-Mimicking Protein. Biomacromolecules 2024; 25:1759-1774. [PMID: 38343096 PMCID: PMC10934265 DOI: 10.1021/acs.biomac.3c01239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2023] [Revised: 01/31/2024] [Accepted: 01/31/2024] [Indexed: 03/12/2024]
Abstract
Despite the considerable interest in the recombinant production of synthetic spider silk fibers that possess mechanical properties similar to those of native spider silks, such as the cost-effectiveness, tunability, and scalability realization, is still lacking. To address this long-standing challenge, we have constructed an artificial spider silk gene using Golden Gate assembly for the recombinant bacterial production of dragline-mimicking silk, incorporating all the essential components: the N-terminal domain, a 33-residue-long major-ampullate-spidroin-inspired segment repeated 16 times, and the C-terminal domain (N16C). This designed silk-like protein was successfully expressed in Escherichia coli, purified, and cast into films from formic acid. We produced uniformly 13C-15N-labeled N16C films and employed solid-state magic-angle spinning nuclear magnetic resonance (NMR) for characterization. Thus, we could demonstrate that our bioengineered silk-like protein self-assembles into a film where, when hydrated, the solvent-exposed layer of the rigid, β-nanocrystalline polyalanine core undergoes a transition to an α-helical structure, gaining mobility to the extent that it fully dissolves in water and transforms into a highly dynamic random coil. This hydration-induced behavior induces chain dynamics in the glycine-rich amorphous soft segments on the microsecond time scale, contributing to the elasticity of the solid material. Our findings not only reveal the presence of structurally and dynamically distinct segments within the film's superstructure but also highlight the complexity of the self-organization responsible for the exceptional mechanical properties observed in proteins that mimic dragline silk.
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Affiliation(s)
- Dongqing Wu
- Department
of Chemistry, Faculty of Chemistry and Pharmacy, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Anamaria Koscic
- Department
of Chemistry, Faculty of Chemistry and Pharmacy, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Sonja Schneider
- Department
of Chemistry, Faculty of Chemistry and Pharmacy, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Romeo C. A. Dubini
- Department
of Chemistry, Faculty of Chemistry and Pharmacy, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
- Center
for Nanoscience (CeNS), Faculty of Physics, Ludwig-Maximilians-Universität München, 80799 Munich, Germany
| | - Diana C. Rodriguez Camargo
- Department
of Chemistry, Faculty of Chemistry and Pharmacy, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Sabine Schneider
- Department
of Chemistry, Faculty of Chemistry and Pharmacy, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Petra Rovó
- Department
of Chemistry, Faculty of Chemistry and Pharmacy, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
- Institute
of Science and Technology Austria, 3400 Klosterneuburg, Austria
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2
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Yan Z, Zhao P, Yan X, Zhang R. Using Abundant 1H Polarization to Enhance the Sensitivity of Solid-State NMR Spectroscopy. J Phys Chem Lett 2024; 15:1866-1878. [PMID: 38343090 DOI: 10.1021/acs.jpclett.3c03532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
Solid-state NMR spectroscopy has been playing a significant role in elucidating the structures and dynamics of materials and proteins at the atomic level for decades. As an extremely abundant nucleus with a very high gyromagnetic ratio, protons are widely present in most organic/inorganic materials. Thus, this Perspective highlights the advantages of proton detection at fast magic-angle spinning (MAS) and presents strategies to utilize and exhaust 1H polarization to achieve signal sensitivity enhancement of solid-state NMR spectroscopy, enabling substantial time savings and extraction of more structural and dynamics information per unit time. Those strategies include developing sensitivity-enhanced single-channel 1H multidimensional NMR spectroscopy, implementing multiple polarization transfer steps in each scan to enhance low-γ nuclei signals, and making full use of 1H polarization to obtain homonuclear and heteronuclear chemical shift correlation spectra in a single experiment. Finally, outlooks and perspectives are provided regarding the challenges and future for the further development of sensitivity-enhanced proton-based solid-state NMR spectroscopy.
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Affiliation(s)
- Zhiwei Yan
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter (SESM), South China University of Technology, Guangzhou 510640, P. R. China
| | - Peizhi Zhao
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter (SESM), South China University of Technology, Guangzhou 510640, P. R. China
| | - Xiaojing Yan
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter (SESM), South China University of Technology, Guangzhou 510640, P. R. China
| | - Rongchun Zhang
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter (SESM), South China University of Technology, Guangzhou 510640, P. R. China
- Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou 510640, P. R. China
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3
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Tognetti J, Franks WT, Lewandowski JR, Brown SP. Optimisation of 1H PMLG homonuclear decoupling at 60 kHz MAS to enable 15N-1H through-bond heteronuclear correlation solid-state NMR spectroscopy. Phys Chem Chem Phys 2022; 24:20258-20273. [PMID: 35975627 PMCID: PMC9429863 DOI: 10.1039/d2cp01041k] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The Lee–Goldburg condition for homonuclear decoupling in 1H magic-angle spinning (MAS) solid-state NMR sets the angle θ, corresponding to arctan of the ratio of the rf nutation frequency, ν1, to the rf offset, to be the magic angle, θm, equal to tan−1(√2) = 54.7°. At 60 kHz MAS, we report enhanced decoupling compared to MAS alone in a 1H spectrum of 15N-glycine with at θ = 30° for a ν1 of ∼100 kHz at a 1H Larmor frequency, ν0, of 500 MHz and 1 GHz, corresponding to a high chemical shift scaling factor (λCS) of 0.82. At 1 GHz, we also demonstrate enhanced decoupling compared to 60 kHz MAS alone for a lower ν1 of 51 kHz, i.e., a case where the nutation frequency is less than the MAS frequency, with θ = 18°, λCS = 0.92. The ratio of the rotor period to the decoupling cycle time, Ψ = τr/τc, is in the range 0.53 to 0.61. Windowed decoupling using the optimised parameters for a ν1 of ∼100 kHz also gives good performance in a 1H spin-echo experiment, enabling implementation in a 1H-detected 15N–1H cross polarisation (CP)-refocused INEPT heteronuclear correlation NMR experiment. Specifically, initial 15N transverse magnetisation as generated by 1H–15N CP is transferred back to 1H using a refocused INEPT pulse sequence employing windowed 1H decoupling. Such an approach ensures the observation of through-bond N–H connectivities. For 15N-glycine, while the CP-refocused INEPT experiment has a lower sensitivity (∼50%) as compared to a double CP experiment (with a 200 μs 15N to 1H CP contact time), there is selectivity for the directly bonded NH3+ moiety, while intensity is observed for the CH21H resonances in the double CP experiment. Two-dimensional 15N–1H correlation MAS NMR spectra are presented for the dipeptide β-AspAla and the pharmaceutical cimetidine at 60 kHz MAS, both at natural isotopic abundance. For the dipeptide β-AspAla, different build-up dependence on the first spin-echo duration is observed for the NH and NH3+ moieties demonstrating that the experiment could be used to distinguish resonances for different NHx groups. 15N–1H heteronuclear NMR correlation at natural abundance in the solid state via J couplings is enabled by optimisation of phase-modulated Lee–Goldburg (PMLG) 1H homonuclear decoupling during the spin echoes, far from the ideal magic-angle condition.![]()
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Affiliation(s)
- Jacqueline Tognetti
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK
- Department of Physics, University of Warwick, Coventry CV4 7AL, UK.
| | - W Trent Franks
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK
- Department of Physics, University of Warwick, Coventry CV4 7AL, UK.
| | | | - Steven P Brown
- Department of Physics, University of Warwick, Coventry CV4 7AL, UK.
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4
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Wang Z, Hanrahan MP, Kobayashi T, Perras FA, Chen Y, Engelke F, Reiter C, Purea A, Rossini AJ, Pruski M. Combining fast magic angle spinning dynamic nuclear polarization with indirect detection to further enhance the sensitivity of solid-state NMR spectroscopy. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2020; 109:101685. [PMID: 32932182 DOI: 10.1016/j.ssnmr.2020.101685] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 07/24/2020] [Accepted: 07/28/2020] [Indexed: 06/11/2023]
Abstract
Dynamic nuclear polarization (DNP) and indirect detection are two commonly applied approaches for enhancing the sensitivity of solid-state NMR spectroscopy. However, their use in tandem has not yet been investigated. With the advent of low-temperature fast magic angle spinning (MAS) probes with 1.3-mm diameter rotors capable of MAS at 40 kHz it becomes feasible to combine these two techniques. In this study, we performed DNP-enhanced 2D indirectly detected heteronuclear correlation (idHETCOR) experiments on 13C, 15N, 113Cd and 89Y nuclei in functionalized mesoporous silica, CdS nanoparticles, and Y2O3 nanoparticles. The sensitivity of the 2D idHETCOR experiments was compared with those of DNP-enhanced directly-detected 1D cross polarization (CP) and 2D HETCOR experiments performed with a standard 3.2-mm rotor. Due to low CP polarization transfer efficiencies and large proton linewidth, the sensitivity gains achieved by indirect detection alone were lower than in conventional (non-DNP) experiments. Nevertheless, despite the smaller sample volume the 2D idHETCOR experiments showed better absolute sensitivities than 2D HETCOR experiments for nuclei with the lowest gyromagnetic ratios. For 89Y, 2D idHETCOR provided 8.2 times better sensitivity than the 1 D89Y-detected CP experiment performed with a 3.2-mm rotor.
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Affiliation(s)
- Zhuoran Wang
- U.S. DOE Ames Laboratory, Iowa State University, Ames, IA, 50011-3020, United States; Department of Chemistry, Iowa State University, Ames, IA, 50011-3020, United States
| | - Michael P Hanrahan
- U.S. DOE Ames Laboratory, Iowa State University, Ames, IA, 50011-3020, United States; Department of Chemistry, Iowa State University, Ames, IA, 50011-3020, United States
| | - Takeshi Kobayashi
- U.S. DOE Ames Laboratory, Iowa State University, Ames, IA, 50011-3020, United States
| | - Frédéric A Perras
- U.S. DOE Ames Laboratory, Iowa State University, Ames, IA, 50011-3020, United States
| | - Yunhua Chen
- U.S. DOE Ames Laboratory, Iowa State University, Ames, IA, 50011-3020, United States; Department of Chemistry, Iowa State University, Ames, IA, 50011-3020, United States
| | | | | | - Armin Purea
- Bruker Biospin, 76287, Rheinstetten, Germany
| | - Aaron J Rossini
- U.S. DOE Ames Laboratory, Iowa State University, Ames, IA, 50011-3020, United States; Department of Chemistry, Iowa State University, Ames, IA, 50011-3020, United States.
| | - Marek Pruski
- U.S. DOE Ames Laboratory, Iowa State University, Ames, IA, 50011-3020, United States; Department of Chemistry, Iowa State University, Ames, IA, 50011-3020, United States.
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5
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Asakura T. Structure and Dynamics of Spider Silk Studied with Solid-State Nuclear Magnetic Resonance and Molecular Dynamics Simulation. Molecules 2020; 25:E2634. [PMID: 32517041 PMCID: PMC7321385 DOI: 10.3390/molecules25112634] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 06/01/2020] [Accepted: 06/01/2020] [Indexed: 01/01/2023] Open
Abstract
This review will introduce very recent studies using solid-state nuclear magnetic resonance (NMR) and molecular dynamics (MD) simulation on the structure and dynamics of spider dragline silks conducted by the author's research group. Spider dragline silks possess extraordinary mechanical properties by combining high tensile strength with outstanding elongation before breaking, and therefore continue to attract attention of researchers in biology, biochemistry, biophysics, analytical chemistry, polymer technology, textile technology, and tissue engineering. However, the inherently non-crystalline structure means that X-ray diffraction and electron diffraction methods provide only limited information because it is difficult to study the molecular structure of the amorphous region. The most detailed picture of the structure and dynamics of the silks in the solid state experimentally have come from solid-state NMR measurements coupled with stable isotope labeling of the silks and the related silk peptides. In addition, combination of solid-state NMR and MD simulation was very powerful analytical tools to understand the local conformation and dynamics of the spider dragline silk in atomic resolution. In this review, the author will emphasize how solid-state NMR and MD simulation have contributed to a better understanding of the structure and dynamics in the spider dragline silks.
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Affiliation(s)
- Tetsuo Asakura
- Department of Biotechnology, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo 184-8588, Japan
- Department of Biotechnology, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo 184-8588, Japan
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6
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Asakura T, Nishimura A, Aoki A, Naito A. Packing Structure of Antiparallel β-Sheet Polyalanine Region in a Sequential Model Peptide of Nephila clavipes Dragline Silk Studied Using 13C Solid-State NMR and MD Simulation. Biomacromolecules 2019; 20:3884-3894. [PMID: 31449407 DOI: 10.1021/acs.biomac.9b00969] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Packing structures of polyalanine regions, which are considered to be the reason for the extremely high strength of spider dragline silks, were studied using a series of sequential peptides: (Glu)4GlyGlyLeuGlyGlyGlnGlyAlaGly(Ala)nGlyGlyAlaGlyGlnGlyGlyTyrGlyGly(Glu)4 (n = 3-8) using 13C solid-state NMR spectroscopy. The conformations of (Ala)n in the freeze-dried peptides changed gradually with increasing n from random coils to α-helices with partial antiparallel β-sheet (AP-β) structures. Conversely, all the insolubilized peptides, n = 6-8 after low-pH treatment and n = 4-8 after formic acid/methanol treatment, formed AP-β structures with significant amounts of staggered packing arrangements. These results are different from previously obtained results for pure alanine oligopeptides, that is, AP-β (Ala)n formed rectangular packing for less than n = 6 but staggered packings for n ≥ 7. The 13C-labeled peptides were also used to confirm the staggered packing arrangements from NMR dynamics. Furthermore, a MD simulation supported the observed results.
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Affiliation(s)
- Tetsuo Asakura
- Department of Biotechnology , Tokyo University of Agriculture and Technology , Koganei, Tokyo 184-8588 , Japan
| | - Akio Nishimura
- Department of Biotechnology , Tokyo University of Agriculture and Technology , Koganei, Tokyo 184-8588 , Japan
| | - Akihiro Aoki
- Department of Biotechnology , Tokyo University of Agriculture and Technology , Koganei, Tokyo 184-8588 , Japan
| | - Akira Naito
- Department of Biotechnology , Tokyo University of Agriculture and Technology , Koganei, Tokyo 184-8588 , Japan
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7
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Zhang R, Duong NT, Nishiyama Y. Resolution enhancement and proton proximity probed by 3D TQ/DQ/SQ proton NMR spectroscopy under ultrafast magic-angle-spinning beyond 70 kHz. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 304:78-86. [PMID: 31146121 DOI: 10.1016/j.jmr.2019.05.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 05/15/2019] [Accepted: 05/18/2019] [Indexed: 06/09/2023]
Abstract
Proton nuclear magnetic resonance (NMR) in solid state has gained significant attention in recent years due to the remarkable resolution and sensitivity enhancement afforded by ultrafast magic-angle-spinning (MAS). In spite of the substantial suppression of 1H-1H dipolar couplings, the proton spectral resolution is still poor compared to that of 13C or 15N NMR, rendering it challenging for the structural and conformational analysis of complex chemicals or biological solids. Herein, by utilizing the benefits of double-quantum (DQ) and triple-quantum (TQ) coherences, we propose a 3D single-channel pulse sequence that correlates proton triple-quantum/double-quantum/single-quantum (TQ/DQ/SQ) chemical shifts. In addition to the two-spin proximity information, this 3D TQ/DQ/SQ pulse sequence enables more reliable extraction of three-spin proximity information compared to the regular 2D TQ/SQ correlation experiment, which could aid in revealing the proton network in solids. Furthermore, the TQ/DQ slice taken at a specific SQ chemical shift only reveals the local correlations to the corresponding SQ chemical shift, and thus it enables accurate assignments of the proton peaks along the TQ and DQ dimensions and simplifies the interpretation of proton spectra especially for dense proton networks. The high performance of this 3D pulse sequence is well demonstrated on small compounds, L-alanine and a tripeptide, N-formyl-L-methionyl-L-leucyl-L-phenylalanine (MLF). We expect that this new methodology can inspire the development of multidimensional solid-state NMR pulse sequences using the merits of TQ and DQ coherences and enable high-throughput investigations of complex solids using abundant protons.
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Affiliation(s)
- Rongchun Zhang
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Molecular Science and Engineering, South China University of Technology, Guangzhou 510640, PR China.
| | - Nghia Tuan Duong
- NMR Science and Development Division, RIKEN SPring-8 Center, and Nano-Crystallography Unit, RIKEN-JEOL Collaboration Center, Yokohama, Kanagawa 230-0045, Japan
| | - Yusuke Nishiyama
- NMR Science and Development Division, RIKEN SPring-8 Center, and Nano-Crystallography Unit, RIKEN-JEOL Collaboration Center, Yokohama, Kanagawa 230-0045, Japan; JEOL RESONANCE Inc., Musashino, Akishima, Tokyo 196-8558, Japan.
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8
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Makrinich M, Goldbourt A. 1H-Detected quadrupolar spin-lattice relaxation measurements under magic-angle spinning solid-state NMR. Chem Commun (Camb) 2019; 55:5643-5646. [PMID: 31026003 DOI: 10.1039/c9cc01176e] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Proton detection and phase-modulated pulse saturation enable the measurement of spin-lattice relaxation times of "invisible" quadrupolar nuclei with extensively large quadrupolar couplings. For nitrogen-14, efficient cross-polarization is obtained with a long-duration preparation pulse. The experiment paves the way to the characterization of a large variety of materials containing halogens, metals and more.
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Affiliation(s)
- Maria Makrinich
- School of Chemistry, Sackler Faculty of Exact Sciences, Tel Aviv University, Ramat Aviv 6997801, Tel Aviv, Israel.
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9
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Han R, Yang Y, Wang S. Longitudinal Relaxation Optimization Enhances 1 H-Detected HSQC in Solid-State NMR Spectroscopy on Challenging Biological Systems. Chemistry 2019; 25:4115-4122. [PMID: 30632195 DOI: 10.1002/chem.201805327] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Indexed: 11/10/2022]
Abstract
Solid-state (SS) NMR spectroscopy is a powerful technique for studying challenging biological systems, but it often suffers from low sensitivity. A longitudinal relaxation optimization scheme to enhance the signal sensitivity of HSQC experiments in SSNMR spectroscopy is reported. Under the proposed scheme, the 1 H spins of 1 H-X (15 N or 13 C) are selected for signal acquisition, whereas other vast 1 H spins are flipped back to the axis of the static magnetic field to accelerate the spin recovery of the observed 1 H spins, resulting in enhanced sensitivity. Three biological systems are used to evaluate this strategy, including a seven-transmembrane protein, an RNA, and a whole-cell sample. For all three samples, the proposed scheme largely shortens the effective 1 H longitudinal relaxation time and results in a 1.3-2.5-fold gain in sensitivity. The selected systems are representative of challenging biological systems for observation by means of SSNMR spectroscopy; thus indicating the general applicability of this method, which is particularly important for biological samples with a short lifetime or with limited sample quantities.
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Affiliation(s)
- Rong Han
- College of Chemistry and Molecular Engineering and Beijing NMR Center, Peking University, No. 5th, Yiheyuan Rd., Beijing, 100871, P.R. China
| | - Yufei Yang
- College of Chemistry and Molecular Engineering and Beijing NMR Center, Peking University, No. 5th, Yiheyuan Rd., Beijing, 100871, P.R. China
| | - Shenlin Wang
- College of Chemistry and Molecular Engineering and Beijing NMR Center, Peking University, No. 5th, Yiheyuan Rd., Beijing, 100871, P.R. China.,Beijing National Laboratory for Molecular Sciences, Beijing, P.R. China
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10
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Kobayashi T, Perras FA, Chaudhary U, Slowing II, Huang W, Sadow AD, Pruski M. Improved strategies for DNP-enhanced 2D 1H-X heteronuclear correlation spectroscopy of surfaces. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2017; 87:38-44. [PMID: 28834782 DOI: 10.1016/j.ssnmr.2017.08.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 08/04/2017] [Accepted: 08/08/2017] [Indexed: 06/07/2023]
Abstract
We demonstrate that dynamic nuclear polarization (DNP)-enhanced 1H-X heteronuclear correlation (HETCOR) measurements of hydrogen-rich surface species are better accomplished by using proton-free solvents. This approach notably prevents HETCOR spectra from being obfuscated by the solvent-derived signals otherwise present in DNP measurements. Additionally, in the hydrogen-rich materials studied here, which included functionalized mesoporous silica nanoparticles and metal organic frameworks, the use of proton-free solvents afforded higher sensitivity gains than the commonly used solvents containing protons. We also explored the possibility of using a solvent-free sample formulation and the feasibility of indirect detection in DNP-enhanced HETCOR experiments.
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Affiliation(s)
| | | | - Umesh Chaudhary
- Department of Chemistry, Iowa State University, IA 50011, USA
| | - Igor I Slowing
- Ames Laboratory, U.S. Department of Energy, Ames, IA 50011, USA; Department of Chemistry, Iowa State University, IA 50011, USA
| | - Wenyu Huang
- Ames Laboratory, U.S. Department of Energy, Ames, IA 50011, USA; Department of Chemistry, Iowa State University, IA 50011, USA
| | - Aaron D Sadow
- Ames Laboratory, U.S. Department of Energy, Ames, IA 50011, USA; Department of Chemistry, Iowa State University, IA 50011, USA
| | - Marek Pruski
- Ames Laboratory, U.S. Department of Energy, Ames, IA 50011, USA; Department of Chemistry, Iowa State University, IA 50011, USA.
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11
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Venkatesh A, Hanrahan MP, Rossini AJ. Proton detection of MAS solid-state NMR spectra of half-integer quadrupolar nuclei. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2017; 84:171-181. [PMID: 28392024 DOI: 10.1016/j.ssnmr.2017.03.005] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2017] [Revised: 03/25/2017] [Accepted: 03/28/2017] [Indexed: 05/09/2023]
Abstract
Fast magic angle spinning (MAS) and proton detection has found widespread application to enhance the sensitivity of solid-state NMR experiments with spin-1/2 nuclei such as 13C, 15N and 29Si, however, this approach is not yet routinely applied to half-integer quadrupolar nuclei. Here we have investigated the feasibility of using fast MAS and proton detection to enhance the sensitivity of solid-state NMR experiments with half-integer quadrupolar nuclei. The previously described dipolar hetero-nuclear multiple quantum correlation (D-HMQC) and dipolar refocused insensitive nuclei enhanced by polarization transfer (D-RINEPT) pulse sequences were used for proton detection of half-integer quadrupolar nuclei. Quantitative comparisons of signal-to-noise ratios and the sensitivity of proton detected D-HMQC and D-RINEPT and direct detection spin echo and quadrupolar Carr-Purcell Meiboom-Gill (QCPMG) solid-state NMR spectra, demonstrate that one dimensional proton detected experiments can provide sensitivity similar to or exceeding that obtainable with direct detection QCPMG experiments. 2D D-HMQC and D-RINEPT experiments provide less sensitivity than QCPMG experiments but proton detected 2D hetero-nuclear correlation solid-state NMR spectra of half-integer nuclei can still be acquired in about the same time as a 1D spin echo spectrum. Notably, the rarely used D-RINEPT pulse sequence is found to provide similar, or better sensitivity than D-HMQC in some cases. Proton detected D-RINEPT benefits from the short longitudinal relaxation times (T1) normally associated with half-integer quadrupolar nuclei, it can be combined with existing signal enhancement methods for quadrupolar nuclei, and t1-noise in the indirect dimension can easily be removed by pre-saturation of the 1H nuclei. The rapid acquisition of proton detected 2D HETCOR solid-state NMR spectra of a range of half-integer quadrupolar nuclei such as 17O, 27Al, 35Cl and 71Ga is demonstrated.
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Affiliation(s)
- Amrit Venkatesh
- Iowa State University, Department of Chemistry, Ames, IA 50011, USA; US DOE Ames Laboratory, Ames, IA 50011, USA
| | - Michael P Hanrahan
- Iowa State University, Department of Chemistry, Ames, IA 50011, USA; US DOE Ames Laboratory, Ames, IA 50011, USA
| | - Aaron J Rossini
- Iowa State University, Department of Chemistry, Ames, IA 50011, USA; US DOE Ames Laboratory, Ames, IA 50011, USA.
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12
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Zhang R, Mroue KH, Ramamoorthy A. Proton-Based Ultrafast Magic Angle Spinning Solid-State NMR Spectroscopy. Acc Chem Res 2017; 50:1105-1113. [PMID: 28353338 DOI: 10.1021/acs.accounts.7b00082] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Protons are vastly abundant in a wide range of exciting macromolecules and thus can be a powerful probe to investigate the structure and dynamics at atomic resolution using solid-state NMR (ssNMR) spectroscopy. Unfortunately, the high signal sensitivity, afforded by the high natural-abundance and high gyromagnetic ratio of protons, is greatly compromised by severe line broadening due to the very strong 1H-1H dipolar couplings. As a result, protons are rarely used, in spite of the desperate need for enhancing the sensitivity of ssNMR to study a variety of systems that are not amenable for high resolution investigation using other techniques including X-ray crystallography, cryo-electron microscopy, and solution NMR spectroscopy. Thanks to the remarkable improvement in proton spectral resolution afforded by the significant advances in magic-angle-spinning (MAS) probe technology, 1H ssNMR spectroscopy has recently attracted considerable attention in the structural and dynamics studies of various molecular systems. However, it still remains a challenge to obtain narrow 1H spectral lines, especially from proteins, without resorting to deuteration. In this Account, we review recent proton-based ssNMR strategies that have been developed in our laboratory to further improve proton spectral resolution without resorting to chemical deuteration for the purposes of gaining atomistic-level insights into molecular structures of various crystalline solid systems, using small molecules and peptides as illustrative examples. The proton spectral resolution enhancement afforded by the ultrafast MAS frequencies up to 120 kHz is initially discussed, followed by a description of an ensemble of multidimensional NMR pulse sequences, all based on proton detection, that have been developed to obtain in-depth information from dipolar couplings and chemical shift anisotropy (CSA). Simple single channel multidimensional proton NMR experiments could be performed to probe the proximity of protons for structure determination using 1H-1H dipolar couplings and to evaluate the changes in chemical environments as well as the relative orientation to the external magnetic field using proton CSA. Due to the boost in signal sensitivity enabled by proton detection under ultrafast MAS, by virtue of high proton natural abundance and gyromagnetic ratio, proton-detected multidimensional experiments involving low-γ nuclei can now be accomplished within a reasonable time, while the higher dimension also offers additional resolution enhancement. In addition, the application of proton-based ssNMR spectroscopy under ultrafast MAS in various challenging and crystalline systems is also presented. Finally, we briefly discuss the limitations and challenges pertaining to proton-based ssNMR spectroscopy under ultrafast MAS conditions, such as the presence of high-order dipolar couplings, friction-induced sample heating, and limited sample volume. Although there are still a number of challenges that must be circumvented by further developments in radio frequency pulse sequences, MAS probe technology and approaches to prepare NMR-friendly samples, proton-based ssNMR has already gained much popularity in various research domains, especially in proteins where uniform or site-selective deuteration can be relatively easily achieved. In addition, implementation of the recently developed fast data acquisition approaches would also enable further developments in the design and applications of proton-based ultrafast MAS multidimensional ssNMR techniques.
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Affiliation(s)
- Rongchun Zhang
- Biophysics Program and Department
of Chemistry, The University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Kamal H. Mroue
- Biophysics Program and Department
of Chemistry, The University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Ayyalusamy Ramamoorthy
- Biophysics Program and Department
of Chemistry, The University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055, United States
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Quinn CM, Polenova T. Structural biology of supramolecular assemblies by magic-angle spinning NMR spectroscopy. Q Rev Biophys 2017; 50:e1. [PMID: 28093096 PMCID: PMC5483179 DOI: 10.1017/s0033583516000159] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
In recent years, exciting developments in instrument technology and experimental methodology have advanced the field of magic-angle spinning (MAS) nuclear magnetic resonance (NMR) to new heights. Contemporary MAS NMR yields atomic-level insights into structure and dynamics of an astounding range of biological systems, many of which cannot be studied by other methods. With the advent of fast MAS, proton detection, and novel pulse sequences, large supramolecular assemblies, such as cytoskeletal proteins and intact viruses, are now accessible for detailed analysis. In this review, we will discuss the current MAS NMR methodologies that enable characterization of complex biomolecular systems and will present examples of applications to several classes of assemblies comprising bacterial and mammalian cytoskeleton as well as human immunodeficiency virus 1 and bacteriophage viruses. The body of work reviewed herein is representative of the recent advancements in the field, with respect to the complexity of the systems studied, the quality of the data, and the significance to the biology.
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Affiliation(s)
- Caitlin M. Quinn
- University of Delaware, Department of Chemistry and Biochemistry, Newark, DE 19711; Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, PA 15306
| | - Tatyana Polenova
- University of Delaware, Department of Chemistry and Biochemistry, Newark, DE 19711; Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, PA 15306
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Nishiyama Y. Fast magic-angle sample spinning solid-state NMR at 60-100kHz for natural abundance samples. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2016; 78:24-36. [PMID: 27400153 DOI: 10.1016/j.ssnmr.2016.06.002] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 06/07/2016] [Accepted: 06/08/2016] [Indexed: 06/06/2023]
Abstract
In spite of tremendous progress made in pulse sequence designs and sophisticated hardware developments, methods to improve sensitivity and resolution in solid-state NMR (ssNMR) are still emerging. The rate at which sample is spun at magic angle determines the extent to which sensitivity and resolution of NMR spectra are improved. To this end, the prime objective of this article is to give a comprehensive theoretical and experimental framework of fast magic angle spinning (MAS) technique. The engineering design of fast MAS rotors based on spinning rate, sample volume, and sensitivity is presented in detail. Besides, the benefits of fast MAS citing the recent progress in methodology, especially for natural abundance samples are also highlighted. The effect of the MAS rate on (1)H resolution, which is a key to the success of the (1)H inverse detection methods, is described by a simple mathematical factor named as the homogeneity factor k. A comparison between various (1)H inverse detection methods is also presented. Moreover, methods to reduce the number of spinning sidebands (SSBs) for the systems with huge anisotropies in combination with (1)H inverse detection at fast MAS are discussed.
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Affiliation(s)
- Yusuke Nishiyama
- RIKEN CLST-JEOL Collaboration Center, RIKEN, Yokohama, Kanagawa 230-0045, Japan; JEOL RESONANCE Inc., Musashino, Akishima, Tokyo 186-8558, Japan.
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Brauckmann JO, Janssen JWGH, Kentgens APM. High resolution triple resonance micro magic angle spinning NMR spectroscopy of nanoliter sample volumes. Phys Chem Chem Phys 2016; 18:4902-10. [PMID: 26806199 DOI: 10.1039/c5cp07857a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
To be able to study mass-limited samples and small single crystals, a triple resonance micro-magic angle spinning (μMAS) probehead for the application of high-resolution solid-state NMR of nanoliter samples was developed. Due to its excellent rf performance this allows us to explore the limits of proton NMR resolution in strongly coupled solids. Using homonuclear decoupling we obtain unprecedented (1)H linewidths for a single crystal of glycine (Δν(CH2) = 0.14 ppm) at high field (20 T) in a directly detected spectrum. The triple channel design allowed the recording of high-resolution μMAS (13)C-(15)N correlations of [U-(13)C-(15)N] arginine HCl and shows that the superior (1)H resolution opens the way for high-sensitivity inverse detection of heteronuclei even at moderate spinning speeds and rf-fields. Efficient decoupling leads to long coherence times which can be exploited in many correlation experiments.
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Affiliation(s)
- J Ole Brauckmann
- Institute of Molecules and Materials, Radboud University, 6500 GL Nijmegen, Netherlands. and TI-COAST, Science Park 904, 1098 XH Amsterdam, Netherlands
| | - J W G Hans Janssen
- Institute of Molecules and Materials, Radboud University, 6500 GL Nijmegen, Netherlands.
| | - Arno P M Kentgens
- Institute of Molecules and Materials, Radboud University, 6500 GL Nijmegen, Netherlands.
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Zhang R, Ramamoorthy A. Constant-time 2D and 3D through-bond correlation NMR spectroscopy of solids under 60 kHz MAS. J Chem Phys 2016; 144:034202. [PMID: 26801026 PMCID: PMC4723396 DOI: 10.1063/1.4940029] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 01/04/2016] [Indexed: 12/13/2022] Open
Abstract
Establishing connectivity and proximity of nuclei is an important step in elucidating the structure and dynamics of molecules in solids using magic angle spinning (MAS) NMR spectroscopy. Although recent studies have successfully demonstrated the feasibility of proton-detected multidimensional solid-state NMR experiments under ultrafast-MAS frequencies and obtaining high-resolution spectral lines of protons, assignment of proton resonances is a major challenge. In this study, we first re-visit and demonstrate the feasibility of 2D constant-time uniform-sign cross-peak correlation (CTUC-COSY) NMR experiment on rigid solids under ultrafast-MAS conditions, where the sensitivity of the experiment is enhanced by the reduced spin-spin relaxation rate and the use of low radio-frequency power for heteronuclear decoupling during the evolution intervals of the pulse sequence. In addition, we experimentally demonstrate the performance of a proton-detected pulse sequence to obtain a 3D (1)H/(13)C/(1)H chemical shift correlation spectrum by incorporating an additional cross-polarization period in the CTUC-COSY pulse sequence to enable proton chemical shift evolution and proton detection in the incrementable t1 and t3 periods, respectively. In addition to through-space and through-bond (13)C/(1)H and (13)C/(13)C chemical shift correlations, the 3D (1)H/(13)C/(1)H experiment also provides a COSY-type (1)H/(1)H chemical shift correlation spectrum, where only the chemical shifts of those protons, which are bonded to two neighboring carbons, are correlated. By extracting 2D F1/F3 slices ((1)H/(1)H chemical shift correlation spectrum) at different (13)C chemical shift frequencies from the 3D (1)H/(13)C/(1)H spectrum, resonances of proton atoms located close to a specific carbon atom can be identified. Overall, the through-bond and through-space homonuclear/heteronuclear proximities determined from the 3D (1)H/(13)C/(1)H experiment would be useful to study the structure and dynamics of a variety of chemical and biological solids.
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Affiliation(s)
- Rongchun Zhang
- Biophysics and Department of Chemistry, The University of Michigan, Ann Arbor, Michigan 48109-1055, USA
| | - Ayyalusamy Ramamoorthy
- Biophysics and Department of Chemistry, The University of Michigan, Ann Arbor, Michigan 48109-1055, USA
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Zhang R, Nishiyama Y, Ramamoorthy A. Proton-detected 3D (1)H/(13)C/(1)H correlation experiment for structural analysis in rigid solids under ultrafast-MAS above 60 kHz. J Chem Phys 2015; 143:164201. [PMID: 26520504 PMCID: PMC4617735 DOI: 10.1063/1.4933373] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Accepted: 10/06/2015] [Indexed: 02/06/2023] Open
Abstract
A proton-detected 3D (1)H/(13)C/(1)H chemical shift correlation experiment is proposed for the assignment of chemical shift resonances, identification of (13)C-(1)H connectivities, and proximities of (13)C-(1)H and (1)H-(1)H nuclei under ultrafast magic-angle-spinning (ultrafast-MAS) conditions. Ultrafast-MAS is used to suppress all anisotropic interactions including (1)H-(1)H dipolar couplings, while the finite-pulse radio frequency driven dipolar recoupling (fp-RFDR) pulse sequence is used to recouple dipolar couplings among protons and the insensitive nuclei enhanced by polarization transfer technique is used to transfer magnetization between heteronuclear spins. The 3D experiment eliminates signals from non-carbon-bonded protons and non-proton-bonded carbons to enhance spectral resolution. The 2D (F1/F3) (1)H/(1)H and 2D (13)C/(1)H (F2/F3) chemical shift correlation spectra extracted from the 3D spectrum enable the identification of (1)H-(1)H proximity and (13)C-(1)H connectivity. In addition, the 2D (F1/F2) (1)H/(13)C chemical shift correlation spectrum, incorporated with proton magnetization exchange via the fp-RFDR recoupling of (1)H-(1)H dipolar couplings, enables the measurement of proximities between (13)C and even the remote non-carbon-bonded protons. The 3D experiment also gives three-spin proximities of (1)H-(1)H-(13)C chains. Experimental results obtained from powder samples of L-alanine and L-histidine ⋅ H2O ⋅ HCl demonstrate the efficiency of the 3D experiment.
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Affiliation(s)
- Rongchun Zhang
- Biophysics and Department of Chemistry, The University of Michigan, Ann Arbor, Michigan 48109-1055, USA
| | | | - Ayyalusamy Ramamoorthy
- Biophysics and Department of Chemistry, The University of Michigan, Ann Arbor, Michigan 48109-1055, USA
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18
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Zhang R, Ramamoorthy A. Selective excitation enables assignment of proton resonances and (1)H-(1)H distance measurement in ultrafast magic angle spinning solid state NMR spectroscopy. J Chem Phys 2015; 143:034201. [PMID: 26203019 PMCID: PMC4506299 DOI: 10.1063/1.4926834] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 07/03/2015] [Indexed: 11/14/2022] Open
Abstract
Remarkable developments in ultrafast magic angle spinning (MAS) solid-state NMR spectroscopy enabled proton-based high-resolution multidimensional experiments on solids. To fully utilize the benefits rendered by proton-based ultrafast MAS experiments, assignment of (1)H resonances becomes absolutely necessary. Herein, we propose an approach to identify different proton peaks by using dipolar-coupled heteronuclei such as (13)C or (15)N. In this method, after the initial preparation of proton magnetization and cross-polarization to (13)C nuclei, transverse magnetization of desired (13)C nuclei is selectively prepared by using DANTE (Delays Alternating with Nutations for Tailored Excitation) sequence and then, it is transferred to bonded protons with a short-contact-time cross polarization. Our experimental results demonstrate that protons bonded to specific (13)C atoms can be identified and overlapping proton peaks can also be assigned. In contrast to the regular 2D HETCOR experiment, only a few 1D experiments are required for the complete assignment of peaks in the proton spectrum. Furthermore, the finite-pulse radio frequency driven recoupling sequence could be incorporated right after the selection of specific proton signals to monitor the intensity buildup for other proton signals. This enables the extraction of (1)H-(1)H distances between different pairs of protons. Therefore, we believe that the proposed method will greatly aid in fast assignment of peaks in proton spectra and will be useful in the development of proton-based multi-dimensional solid-state NMR experiments to study atomic-level resolution structure and dynamics of solids.
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Affiliation(s)
- Rongchun Zhang
- Biophysics and Department of Chemistry, The University of Michigan, Ann Arbor, Michigan 48109-1055, USA
| | - Ayyalusamy Ramamoorthy
- Biophysics and Department of Chemistry, The University of Michigan, Ann Arbor, Michigan 48109-1055, USA
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Zhang R, Pandey MK, Nishiyama Y, Ramamoorthy A. A Novel High-Resolution and Sensitivity-Enhanced Three-Dimensional Solid-State NMR Experiment Under Ultrafast Magic Angle Spinning Conditions. Sci Rep 2015; 5:11810. [PMID: 26138791 PMCID: PMC4490345 DOI: 10.1038/srep11810] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2015] [Accepted: 05/19/2015] [Indexed: 12/22/2022] Open
Abstract
Although magic angle spinning (MAS) solid-state NMR is a powerful technique to obtain atomic-resolution insights into the structure and dynamics of a variety of chemical and biological solids, poor sensitivity has severely limited its applications. In this study, we demonstrate an approach that suitably combines proton-detection, ultrafast-MAS and multiple frequency dimensions to overcome this limitation. With the utilization of proton-proton dipolar recoupling and double quantum (DQ) coherence excitation/reconversion radio-frequency pulses, very high-resolution proton-based 3D NMR spectra that correlate single-quantum (SQ), DQ and SQ coherences of biological solids have been obtained successfully for the first time. The proposed technique requires a very small amount of sample and does not need multiple radio-frequency (RF) channels. It also reveals information about the proximity between a spin and a certain other dipolar-coupled pair of spins in addition to regular SQ/DQ and SQ/SQ correlations. Although 1H spectral resolution is still limited for densely proton-coupled systems, the 3D technique is valuable to study dilute proton systems, such as zeolites, small molecules, or deuterated samples. We also believe that this new methodology will aid in the design of a plethora of multidimensional NMR techniques and enable high-throughput investigation of an exciting class of solids at atomic-level resolution.
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Affiliation(s)
- Rongchun Zhang
- Biophysics and Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Manoj Kumar Pandey
- RIKEN CLST-JEOL collaboration center, RIKEN, Yokohama, Kanagawa 230-0045, Japan
| | - Yusuke Nishiyama
- 1] RIKEN CLST-JEOL collaboration center, RIKEN, Yokohama, Kanagawa 230-0045, Japan [2] JEOL RESONANCE Inc., Musashino, Akishima, Tokyo 196-8558, Japan
| | - Ayyalusamy Ramamoorthy
- Biophysics and Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
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20
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Komatsu T, Kobayashi T, Hatanaka M, Kikuchi J. Profiling planktonic biomass using element-specific, multicomponent nuclear magnetic resonance spectroscopy. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:7056-62. [PMID: 25973714 DOI: 10.1021/acs.est.5b00837] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Planktonic metabolism plays crucial roles in Earth's elemental cycles. Chemical speciation as well as elemental stoichiometry is important for advancing our understanding of planktonic roles in biogeochemical cycles. In this study, a multicomponent solid-state nuclear magnetic resonance (NMR) approach is proposed for chemical speciation of cellular components, using several advanced NMR techniques. Measurements by ssNMR were performed on (13)C and (15)N-labeled Euglena gracilis, a flagellated protist. 3D dipolar-assisted rotational resonance, double-cross-polarization (1)H-(13)C correlation spectroscopy, and (1)H-(13)C solid-state heteronuclear single quantum correlation spectroscopy successively allowed characterization of cellular components. These techniques were then applied to E. gracilis cultured in high and low ammonium media to demonstrate the power of this method for profiling and comparing cellular components. Cellular NMR spectra indicated that ammonium induced both paramylon degradation and amination. Arginine was stored as a nitrogen reserve and ammonium replaced by arginine catabolism via the arginine dihydrolase pathway. (15)N and (31)P cellular ssNMR indicated arginine and polyphosphate accumulation in E. gracilis, respectively. This chemical speciation technique will contribute to environmental research by providing detailed information on environmental chemical properties.
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Affiliation(s)
- Takanori Komatsu
- †RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan
- ‡Graduate School of Medical Life Science, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan
| | - Toshiya Kobayashi
- ‡Graduate School of Medical Life Science, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan
| | - Minoru Hatanaka
- §Bruker Biospin K. K., 3-9, Moriya-cho, Kanagawa-ku, Yokohama, 221-0022, Japan
| | - Jun Kikuchi
- †RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan
- ‡Graduate School of Medical Life Science, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan
- ∥Graduate School of Bioagricultural Sciences and School of Agricultural Sciences, Nagoya University, 1 Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
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Quinn CM, Lu M, Suiter CL, Hou G, Zhang H, Polenova T. Magic angle spinning NMR of viruses. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2015; 86-87:21-40. [PMID: 25919197 PMCID: PMC4413014 DOI: 10.1016/j.pnmrs.2015.02.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Revised: 01/27/2015] [Accepted: 02/08/2015] [Indexed: 05/02/2023]
Abstract
Viruses, relatively simple pathogens, are able to replicate in many living organisms and to adapt to various environments. Conventional atomic-resolution structural biology techniques, X-ray crystallography and solution NMR spectroscopy provided abundant information on the structures of individual proteins and nucleic acids comprising viruses; however, viral assemblies are not amenable to analysis by these techniques because of their large size, insolubility, and inherent lack of long-range order. In this article, we review the recent advances in magic angle spinning NMR spectroscopy that enabled atomic-resolution analysis of structure and dynamics of large viral systems and give examples of several exciting case studies.
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Affiliation(s)
- Caitlin M Quinn
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States; Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA 15261, United States.
| | - Manman Lu
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States; Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA 15261, United States.
| | - Christopher L Suiter
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States; Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA 15261, United States.
| | - Guangjin Hou
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States; Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA 15261, United States.
| | - Huilan Zhang
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States.
| | - Tatyana Polenova
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States; Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA 15261, United States.
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Suiter CL, Quinn CM, Lu M, Hou G, Zhang H, Polenova T. MAS NMR of HIV-1 protein assemblies. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2015; 253:10-22. [PMID: 25797001 PMCID: PMC4432874 DOI: 10.1016/j.jmr.2014.12.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Revised: 12/08/2014] [Accepted: 12/17/2014] [Indexed: 06/04/2023]
Abstract
The negative global impact of the AIDS pandemic is well known. In this perspective article, the utility of magic angle spinning (MAS) NMR spectroscopy to answer pressing questions related to the structure and dynamics of HIV-1 protein assemblies is examined. In recent years, MAS NMR has undergone major technological developments enabling studies of large viral assemblies. We discuss some of these evolving methods and technologies and provide a perspective on the current state of MAS NMR as applied to the investigations into structure and dynamics of HIV-1 assemblies of CA capsid protein and of Gag maturation intermediates.
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Affiliation(s)
- Christopher L Suiter
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States; Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA 15261, United States.
| | - Caitlin M Quinn
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States; Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA 15261, United States.
| | - Manman Lu
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States; Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA 15261, United States.
| | - Guangjin Hou
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States; Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA 15261, United States.
| | - Huilan Zhang
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States.
| | - Tatyana Polenova
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States; Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA 15261, United States.
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Zhang R, Nishiyama Y, Sun P, Ramamoorthy A. Phase cycling schemes for finite-pulse-RFDR MAS solid state NMR experiments. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2015; 252:55-66. [PMID: 25655451 PMCID: PMC4380770 DOI: 10.1016/j.jmr.2014.12.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2014] [Revised: 12/07/2014] [Accepted: 12/17/2014] [Indexed: 05/04/2023]
Abstract
The finite-pulse radio frequency driven dipolar recoupling (fp-RFDR) pulse sequence is used in 2D homonuclear chemical shift correlation experiments under magic angle spinning (MAS). A recent study demonstrated the advantages of using a short phase cycle, XY4, and its super-cycle, XY4(1)4, for the fp-RFDR pulse sequence employed in 2D (1)H/(1)H single-quantum/single-quantum correlation experiments under ultrafast MAS conditions. In this study, we report a comprehensive analysis on the dipolar recoupling efficiencies of XY4, XY4(1)2, XY4(1)3, XY4(1)4, and XY8(1)4 phase cycles under different spinning speeds ranging from 10 to 100 kHz. The theoretical calculations reveal the presence of second-order terms (T(10)T(2,±2), T(1,±1)T(2,±1), etc.) in the recoupled homonuclear dipolar coupling Hamiltonian only when the basic XY4 phase cycle is utilized, making it advantageous for proton-proton magnetization transfer under ultrafast MAS conditions. It is also found that the recoupling efficiency of fp-RFDR is quite dependent on the duty factor (τ180/τR) as well as on the strength of homonuclear dipolar couplings. The rate of longitudinal magnetization transfer increases linearly with the duty factor of fp-RFDR for all the XY-based phase cycles investigated in this study. Examination of the performances of different phase cycles against chemical shift offset and RF field inhomogeneity effects revealed that XY4(1)4 is the most tolerant phase cycle, while the shortest phase cycle XY4 suppressed the RF field inhomogeneity effects most efficiently under slow spinning speeds. Our results suggest that the difference in the fp-RFDR recoupling efficiencies decreases with the increasing MAS speed, while ultrafast (>60 kHz) spinning speed is advantageous as it recouples a large amount of homonuclear dipolar couplings and therefore enable fast magnetization exchange. The effects of higher-order terms and cross terms between various interactions in the effective Hamiltonian of fp-RFDR are also analyzed using numerical simulations for various phase cycles. Results obtained via numerical simulations are in excellent agreement with ultrafast MAS experimental results from the powder samples of glycine and l-alanine.
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Affiliation(s)
- Rongchun Zhang
- Biophysics and Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Yusuke Nishiyama
- JEOL RESONANCE Inc., Musashino, Akishima, Tokyo 196-8558, Japan; RIKEN CLST-JEOL Collaboration Center, RIKEN, Yokohama, Kanagawa 230-0045, Japan
| | - Pingchuan Sun
- Key Laboratory of Functional Polymer Materials of Ministry of Education and College of Chemistry, Nankai University, Tianjin 300071, PR China
| | - Ayyalusamy Ramamoorthy
- Biophysics and Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA.
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Zhang R, Damron J, Vosegaard T, Ramamoorthy A. A cross-polarization based rotating-frame separated-local-field NMR experiment under ultrafast MAS conditions. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2015; 250:37-44. [PMID: 25486635 PMCID: PMC4286468 DOI: 10.1016/j.jmr.2014.10.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 10/16/2014] [Accepted: 10/26/2014] [Indexed: 05/04/2023]
Abstract
Rotating-frame separated-local-field solid-state NMR experiments measure highly resolved heteronuclear dipolar couplings which, in turn, provide valuable interatomic distances for structural and dynamic studies of molecules in the solid-state. Though many different rotating-frame SLF sequences have been put forth, recent advances in ultrafast MAS technology have considerably simplified pulse sequence requirements due to the suppression of proton-proton dipolar interactions. In this study we revisit a simple two-dimensional (1)H-(13)C dipolar coupling/chemical shift correlation experiment using (13)C detected cross-polarization with a variable contact time (CPVC) and systematically study the conditions for its optimal performance at 60 kHz MAS. In addition, we demonstrate the feasibility of a proton-detected version of the CPVC experiment. The theoretical analysis of the CPVC pulse sequence under different Hartmann-Hahn matching conditions confirms that it performs optimally under the ZQ (w1H-w1C=±wr) condition for polarization transfer. The limits of the cross polarization process are explored and precisely defined as a function of offset and Hartmann-Hahn mismatch via spin dynamics simulation and experiments on a powder sample of uniformly (13)C-labeled L-isoleucine. Our results show that the performance of the CPVC sequence and subsequent determination of (1)H-(13)C dipolar couplings are insensitive to (1)H/(13)C frequency offset frequency when high RF fields are used on both RF channels. Conversely, the CPVC sequence is quite sensitive to the Hartmann-Hahn mismatch, particularly for systems with weak heteronuclear dipolar couplings. We demonstrate the use of the CPVC based SLF experiment as a tool to identify different carbon groups, and hope to motivate the exploration of more sophisticated (1)H detected avenues for ultrafast MAS.
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Affiliation(s)
- Rongchun Zhang
- Biophysics and Department of Chemistry, The University of Michigan, Ann Arbor, MI 48109-1055, United States
| | - Joshua Damron
- Biophysics and Department of Chemistry, The University of Michigan, Ann Arbor, MI 48109-1055, United States
| | - Thomas Vosegaard
- Center for Insoluble Protein Structures (inSPIN), Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Ayyalusamy Ramamoorthy
- Biophysics and Department of Chemistry, The University of Michigan, Ann Arbor, MI 48109-1055, United States.
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25
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Paudel A, Geppi M, Mooter GVD. Structural and Dynamic Properties of Amorphous Solid Dispersions: The Role of Solid-State Nuclear Magnetic Resonance Spectroscopy and Relaxometry. J Pharm Sci 2014; 103:2635-2662. [DOI: 10.1002/jps.23966] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 03/17/2014] [Accepted: 03/17/2014] [Indexed: 01/17/2023]
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26
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Zhang R, Ramamoorthy A. Performance of RINEPT is amplified by dipolar couplings under ultrafast MAS conditions. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2014; 243:85-92. [PMID: 24792960 PMCID: PMC4057659 DOI: 10.1016/j.jmr.2014.03.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 03/27/2014] [Accepted: 03/31/2014] [Indexed: 05/04/2023]
Abstract
The refocused insensitive nuclei enhanced by polarization transfer (RINEPT) technique is commonly used for heteronuclear polarization transfer in solution and solid-state NMR spectroscopy. Suppression of dipolar couplings, either by fast molecular motions in solution or by a combination of MAS and multiple pulse sequences in solids, enables the polarization transfer via scalar couplings. However, the presence of unsuppressed dipolar couplings could alter the functioning of RINEPT, particularly under fast/ultrafast MAS conditions. In this study, we demonstrate, through experiments on rigid solids complemented by numerical simulations, that the polarization transfer efficiency of RINEPT is dependent on the MAS frequency. In addition, we show that heteronuclear dipolar coupling is the dominant factor in the polarization transfer, which is strengthened by the presence of (1)H-(1)H dipolar couplings. In fact, the simultaneous presence of homonuclear and heteronuclear dipolar couplings is the premise for the polarization transfer by RINEPT, whereas the scalar coupling plays an insignificant role under ultrafast MAS conditions on rigid solids. Our results additionally reveal that the polarization transfer efficiency decreases with the increasing duration of RF pulses used in the RINEPT sequence.
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Affiliation(s)
- Rongchun Zhang
- Biophysics and Department of Chemistry, The University of Michigan, Ann Arbor, MI 48109-1055, USA; School of Physics, Nankai University, Tianjin 300071, PR China
| | - Ayyalusamy Ramamoorthy
- Biophysics and Department of Chemistry, The University of Michigan, Ann Arbor, MI 48109-1055, USA.
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27
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Nielsen JT, Kulminskaya N, Bjerring M, Nielsen NC. Automated robust and accurate assignment of protein resonances for solid state NMR. JOURNAL OF BIOMOLECULAR NMR 2014; 59:119-34. [PMID: 24817190 DOI: 10.1007/s10858-014-9835-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Accepted: 04/29/2014] [Indexed: 05/26/2023]
Abstract
The process of resonance assignment represents a time-consuming and potentially error-prone bottleneck in structural studies of proteins by solid-state NMR (ssNMR). Software for the automation of this process is therefore of high interest. Procedures developed through the last decades for solution-state NMR are not directly applicable for ssNMR due to the inherently lower data quality caused by lower sensitivity and broader lines, leading to overlap between peaks. Recently, the first efforts towards procedures specifically aimed for ssNMR have been realized (Schmidt et al. in J Biomol NMR 56(3):243-254, 2013). Here we present a robust automatic method, which can accurately assign protein resonances using peak lists from a small set of simple 2D and 3D ssNMR experiments, applicable in cases with low sensitivity. The method is demonstrated on three uniformly (13)C, (15)N labeled biomolecules with different challenges on the assignments. In particular, for the immunoglobulin binding domain B1 of streptococcal protein G automatic assignment shows 100% accuracy for the backbone resonances and 91.8% when including all side chain carbons. It is demonstrated, by using a procedure for generating artificial spectra with increasing line widths, that our method, GAMES_ASSIGN can handle a significant amount of overlapping peaks in the assignment. The impact of including different ssNMR experiments is evaluated as well.
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Affiliation(s)
- Jakob Toudahl Nielsen
- Center for Insoluble Protein Structures (inSPIN), Interdisciplinary Nanoscience Center (iNANO), Department of Chemistry, Aarhus University, Gustav Wieds Vej 14, 8000, Aarhus C, Denmark,
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28
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Althaus SM, Mao K, Stringer JA, Kobayashi T, Pruski M. Indirectly detected heteronuclear correlation solid-state NMR spectroscopy of naturally abundant 15N nuclei. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2014; 57-58:17-21. [PMID: 24287060 DOI: 10.1016/j.ssnmr.2013.11.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 10/22/2013] [Accepted: 11/01/2013] [Indexed: 06/02/2023]
Abstract
Two-dimensional indirectly detected through-space and through-bond (1)H{(15)N} solid-state NMR experiments utilizing fast magic angle spinning (MAS) and homonuclear multipulse (1)H decoupling are evaluated. Remarkable efficiency of polarization transfer can be achieved at a MAS rate of 40 kHz by both cross-polarization and INEPT, which makes these methods applicable for routine characterizations of natural abundance solids. The first measurement of 2D (1)H{(15)N} HETCOR spectrum of natural abundance surface species is also reported.
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Affiliation(s)
- Stacey M Althaus
- U.S. DOE Ames Laboratory, Ames, IA 50011-3020, USA; Department of Chemistry, Iowa State University, Ames, IA 50011-3020, USA
| | - Kanmi Mao
- U.S. DOE Ames Laboratory, Ames, IA 50011-3020, USA; Department of Chemistry, Iowa State University, Ames, IA 50011-3020, USA
| | - John A Stringer
- Agilent Technologies, 900 South Taft, Loveland, CO 80537, USA
| | - Takeshi Kobayashi
- Department of Chemistry, Iowa State University, Ames, IA 50011-3020, USA
| | - Marek Pruski
- U.S. DOE Ames Laboratory, Ames, IA 50011-3020, USA; Department of Chemistry, Iowa State University, Ames, IA 50011-3020, USA.
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29
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Asakura T, Suzuki Y, Nakazawa Y, Yazawa K, Holland GP, Yarger JL. Silk structure studied with nuclear magnetic resonance. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2013; 69:23-68. [PMID: 23465642 DOI: 10.1016/j.pnmrs.2012.08.001] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Accepted: 08/13/2012] [Indexed: 06/01/2023]
Affiliation(s)
- Tetsuo Asakura
- Department of Biotechnology, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan.
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Ohgo K, Niemczura WP, Seacat BC, Wise SG, Weiss AS, Kumashiro KK. Resolving nitrogen-15 and proton chemical shifts for mobile segments of elastin with two-dimensional NMR spectroscopy. J Biol Chem 2012; 287:18201-9. [PMID: 22474297 DOI: 10.1074/jbc.m111.285163] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In this study, one- and two-dimensional NMR experiments are applied to uniformly (15)N-enriched synthetic elastin, a recombinant human tropoelastin that has been cross-linked to form an elastic hydrogel. Hydrated elastin is characterized by large segments that undergo "liquid-like" motions that limit the efficiency of cross-polarization. The refocused insensitive nuclei enhanced by polarization transfer experiment is used to target these extensive, mobile regions of this protein. Numerous peaks are detected in the backbone amide region of the protein, and their chemical shifts indicate the completely unstructured, "random coil" model for elastin is unlikely. Instead, more evidence is gathered that supports a characteristic ensemble of conformations in this rubber-like protein.
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Affiliation(s)
- Kosuke Ohgo
- Department of Chemistry, University of Hawaii, Honolulu, Hawaii 96822, USA
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31
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Brown SP. Applications of high-resolution 1H solid-state NMR. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2012; 41:1-27. [PMID: 22177472 DOI: 10.1016/j.ssnmr.2011.11.006] [Citation(s) in RCA: 182] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2011] [Revised: 11/15/2011] [Accepted: 11/16/2011] [Indexed: 05/25/2023]
Abstract
This article reviews the large increase in applications of high-resolution (1)H magic-angle spinning (MAS) solid-state NMR, in particular two-dimensional heteronuclear and homonuclear (double-quantum and spin-diffusion NOESY-like exchange) experiments, in the last five years. These applications benefit from faster MAS frequencies (up to 80 kHz), higher magnetic fields (up to 1 GHz) and pulse sequence developments (e.g., homonuclear decoupling sequences applicable under moderate and fast MAS). (1)H solid-state NMR techniques are shown to provide unique structural insight for a diverse range of systems including pharmaceuticals, self-assembled supramolecular structures and silica-based inorganic-organic materials, such as microporous and mesoporous materials and heterogeneous organometallic catalysts, for which single-crystal diffraction structures cannot be obtained. The power of NMR crystallography approaches that combine experiment with first-principles calculations of NMR parameters (notably using the GIPAW approach) are demonstrated, e.g., to yield quantitative insight into hydrogen-bonding and aromatic CH-π interactions, as well as to generate trial three-dimensional packing arrangements. It is shown how temperature-dependent changes in the (1)H chemical shift, linewidth and DQ-filtered signal intensity can be analysed to determine the thermodynamics and kinetics of molecular level processes, such as the making and breaking of hydrogen bonds, with particular application to proton-conducting materials. Other applications to polymers and biopolymers, inorganic compounds and bioinorganic systems, paramagnetic compounds and proteins are presented. The potential of new technological advances such as DNP methods and new microcoil designs is described.
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Affiliation(s)
- Steven P Brown
- Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom.
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32
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Nishiyama Y, Lu X, Trébosc J, Lafon O, Gan Z, Madhu PK, Amoureux JP. Practical choice of ¹H-¹H decoupling schemes in through-bond ¹H-{X} HMQC experiments at ultra-fast MAS. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 214:151-158. [PMID: 22130518 DOI: 10.1016/j.jmr.2011.10.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Revised: 10/05/2011] [Accepted: 10/28/2011] [Indexed: 05/31/2023]
Abstract
Three (1)H-(1)H homonuclear dipolar decoupling schemes for (1)H indirect detection measurements at very fast MAS are compared. The sequences require the following conditions: (i) being operable at very fast MAS, (ii) a long T(2)(') value, (iii) a large scaling factor, (iv) a small number of adjustable parameters, (v) an acquisition window, (vi) a low rf-power requirement, and (vii) a z-rotation feature. To satisfy these conditions a modified sequence named TIlted Magic-Echo Sandwich with zero degree sandwich pulse (TIMES(0)) is introduced. The basic elements of TIMES(0) consist of one sampling window and two phase-ramped irradiations, which realize alternating positive and negative 360° rotations of (1)H magnetization around an effective field tilted with an angle θ from the B(0) axis. The TIMES(0) sequence benefits from very large chemical shift scaling factors at ultra-fast MAS that reach κ(cs)=0.90 for θ=25° at ν(r)=80kHz MAS and only four adjustable parameters, resulting in easy setup. Long κ(cs)T(2)(') values, where T(2)(') is a irreversible proton transverse relaxation time, greatly enhance the sensitivity in (1)H-{(13)C} through-bond J-HMQC (Heteronuclear Multiple-Quantum Coherence) measurements with (1)H-(1)H decoupling during magnetization transfer periods. Although similar sensitivity can be obtained with through-space D-HMQC sequences, in which (13)C-(1)H dipolar interactions are recoupled, J-HMQC experiments incorporating (1)H-(1)H decoupling benefit from lower t(1)-noise, more uniform excitation of both CH, CH(2) and CH(3) moieties, and easier identification of through-bond connectivities.
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Affiliation(s)
- Yusuke Nishiyama
- JEOL RESONANCE Inc., 3-1-2 Musashino, Akishima, Tokyo 196-8558, Japan.
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33
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Demers JP, Chevelkov V, Lange A. Progress in correlation spectroscopy at ultra-fast magic-angle spinning: basic building blocks and complex experiments for the study of protein structure and dynamics. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2011; 40:101-113. [PMID: 21880471 DOI: 10.1016/j.ssnmr.2011.07.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Revised: 07/21/2011] [Accepted: 07/22/2011] [Indexed: 05/31/2023]
Abstract
Recent progress in multi-dimensional solid-state NMR correlation spectroscopy at high static magnetic fields and ultra-fast magic-angle spinning is discussed. A focus of the review is on applications to protein resonance assignment and structure determination as well as on the characterization of protein dynamics in the solid state. First, the consequences of ultra-fast spinning on sensitivity and sample heating are considered. Recoupling and decoupling techniques at ultra-fast MAS are then presented, as well as more complex experiments assembled from these basic building blocks. Furthermore, we discuss new avenues in biomolecular solid-state NMR spectroscopy that become feasible in the ultra-fast spinning regime, such as sensitivity enhancement based on paramagnetic doping, and the prospect of direct proton detection.
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Affiliation(s)
- Jean-Philippe Demers
- Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
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34
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Chatterjee PB, Goncharov-Zapata O, Quinn LL, Hou G, Hamaed H, Schurko RW, Polenova T, Crans DC. Characterization of noninnocent metal complexes using solid-state NMR spectroscopy: o-dioxolene vanadium complexes. Inorg Chem 2011; 50:9794-803. [PMID: 21842875 DOI: 10.1021/ic200046k] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
(51)V solid-state NMR (SSNMR) studies of a series of noninnocent vanadium(V) catechol complexes have been conducted to evaluate the possibility that (51)V NMR observables, quadrupolar and chemical shift anisotropies, and electronic structures of such compounds can be used to characterize these compounds. The vanadium(V) catechol complexes described in these studies have relatively small quadrupolar coupling constants, which cover a surprisingly small range from 3.4 to 4.2 MHz. On the other hand, isotropic (51)V NMR chemical shifts cover a wide range from -200 to 400 ppm in solution and from -219 to 530 ppm in the solid state. A linear correlation of (51)V NMR isotropic solution and solid-state chemical shifts of complexes containing noninnocent ligands is observed. These experimental results provide the information needed for the application of (51)V SSNMR spectroscopy in characterizing the electronic properties of a wide variety of vanadium-containing systems and, in particular, those containing noninnocent ligands and that have chemical shifts outside the populated range of -300 to -700 ppm. The studies presented in this report demonstrate that the small quadrupolar couplings covering a narrow range of values reflect the symmetric electronic charge distribution, which is also similar across these complexes. These quadrupolar interaction parameters alone are not sufficient to capture the rich electronic structure of these complexes. In contrast, the chemical shift anisotropy tensor elements accessible from (51)V SSNMR experiments are a highly sensitive probe of subtle differences in electronic distribution and orbital occupancy in these compounds. Quantum chemical (density functional theory) calculations of NMR parameters for [VO(hshed)(Cat)] yield a (51)V chemical shift anisotropy tensor in reasonable agreement with the experimental results, but surprisingly the calculated quadrupolar coupling constant is significantly greater than the experimental value. The studies demonstrate that substitution of the catechol ligand with electron-donating groups results in an increase in the HOMO-LUMO gap and can be directly followed by an upfield shift for the vanadium catechol complex. In contrast, substitution of the catechol ligand with electron-withdrawing groups results in a decrease in the HOMO-LUMO gap and can directly be followed by a downfield shift for the complex. The vanadium catechol complexes were used in this work because (51)V is a half-integer quadrupolar nucleus whose NMR observables are highly sensitive to the local environment. However, the results are general and could be extended to other redox-active complexes that exhibit coordination chemistry similar to that of the vanadium catechol complexes.
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Affiliation(s)
- Pabitra B Chatterjee
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, USA
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