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Xiao H, Zhang Z, Kang H, Yang J. Solid-State NMR Double-Quantum Dipolar Recoupling Enhanced by Additional Phase Modulation. Chemphyschem 2023; 24:e202300141. [PMID: 37309720 DOI: 10.1002/cphc.202300141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 06/02/2023] [Accepted: 06/12/2023] [Indexed: 06/14/2023]
Abstract
Additional phase modulation (APM) is proposed to generally enhance the theoretical efficiency of homonuclear double-quantum (DQ) recoupling in solid-state NMR. APM applies an additional phase list to DQ recoupling in steps of an entire block. The sine-based phase list can enhance the theoretical efficiency by 15-30 %, from 0.52 to 0.68 (non-γ-encoded recoupling) or from 0.73 to 0.84 (γ-encoded recoupling), with doubled recoupling time. The genetic-algorithm (GA) optimized APM can adiabatically enhance the efficiency to ∼1.0 at longer times. The concept of APM has been tested on SPR-51 , BaBa, and SPR-31 , which represent γ-encoded recoupling, non-γ-encoded recoupling, and another kind beyond the former two, respectively. Simulations reveal that enhancements from APM are due to the activation of more crystallites in the powder. Experiments on 2,3-13 C labeled alanine are used to validate the APM recoupling. This new concept shall shed light on developing more efficient homonuclear recoupling methods.
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Affiliation(s)
- Hang Xiao
- National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, Hubei, 430071, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhengfeng Zhang
- National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, Hubei, 430071, China
- Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
| | - Huimin Kang
- National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, Hubei, 430071, China
| | - Jun Yang
- National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, Hubei, 430071, China
- Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
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Nimerovsky E, Najbauer EÉ, Becker S, Andreas LB. Great Offset Difference Internuclear Selective Transfer. J Phys Chem Lett 2023; 14:3939-3945. [PMID: 37078685 PMCID: PMC10150390 DOI: 10.1021/acs.jpclett.3c00194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Carbon-carbon dipolar recoupling sequences are frequently used building blocks in routine magic-angle spinning NMR experiments. While broadband homonuclear first-order dipolar recoupling sequences mainly excite intra-residue correlations, selective methods can detect inter-residue transfers and long-range correlations. Here, we present the great offset difference internuclear selective transfer (GODIST) pulse sequence optimized for selective carbonyl or aliphatic recoupling at fast magic-angle spinning, here, 55 kHz. We observe a 3- to 5-fold increase in intensities compared with broadband RFDR recoupling for perdeuterated microcrystalline SH3 and for the membrane protein influenza A M2 in lipid bilayers. In 3D (H)COCO(N)H and (H)CO(CO)NH spectra, inter-residue carbonyl-carbonyl correlations up to about 5 Å are observed in uniformly 13C-labeled proteins.
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Affiliation(s)
- Evgeny Nimerovsky
- Department of NMR-based Structural Biology, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, Göttingen 37077, Germany
| | - Eszter Éva Najbauer
- Department of NMR-based Structural Biology, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, Göttingen 37077, Germany
| | - Stefan Becker
- Department of NMR-based Structural Biology, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, Göttingen 37077, Germany
| | - Loren B Andreas
- Department of NMR-based Structural Biology, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, Göttingen 37077, Germany
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Abstract
In the last two decades, solid-state nuclear magnetic resonance (ssNMR) spectroscopy has transformed from a spectroscopic technique investigating small molecules and industrial polymers to a potent tool decrypting structure and underlying dynamics of complex biological systems, such as membrane proteins, fibrils, and assemblies, in near-physiological environments and temperatures. This transformation can be ascribed to improvements in hardware design, sample preparation, pulsed methods, isotope labeling strategies, resolution, and sensitivity. The fundamental engagement between nuclear spins and radio-frequency pulses in the presence of a strong static magnetic field is identical between solution and ssNMR, but the experimental procedures vastly differ because of the absence of molecular tumbling in solids. This review discusses routinely employed state-of-the-art static and MAS pulsed NMR methods relevant for biological samples with rotational correlation times exceeding 100's of nanoseconds. Recent developments in signal filtering approaches, proton methodologies, and multiple acquisition techniques to boost sensitivity and speed up data acquisition at fast MAS are also discussed. Several examples of protein structures (globular, membrane, fibrils, and assemblies) solved with ssNMR spectroscopy have been considered. We also discuss integrated approaches to structurally characterize challenging biological systems and some newly emanating subdisciplines in ssNMR spectroscopy.
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Affiliation(s)
- Sahil Ahlawat
- Tata Institute of Fundamental Research Hyderabad, Survey No. 36/P Gopanpally, Serilingampally, Ranga Reddy District, Hyderabad 500046, Telangana, India
| | - Kaustubh R Mote
- Tata Institute of Fundamental Research Hyderabad, Survey No. 36/P Gopanpally, Serilingampally, Ranga Reddy District, Hyderabad 500046, Telangana, India
| | - Nils-Alexander Lakomek
- University of Düsseldorf, Institute for Physical Biology, Universitätsstraße 1, 40225 Düsseldorf, Germany
| | - Vipin Agarwal
- Tata Institute of Fundamental Research Hyderabad, Survey No. 36/P Gopanpally, Serilingampally, Ranga Reddy District, Hyderabad 500046, Telangana, India
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Yu Y, Keil P, Stevensson B, Hansen MR, Edén M. Assessment of new symmetry-based dipolar recoupling schemes for homonuclear magnetization exchange between quadrupolar nuclei in two-dimensional correlation MAS NMR. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2020; 316:106734. [PMID: 32590307 DOI: 10.1016/j.jmr.2020.106734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 04/13/2020] [Accepted: 04/15/2020] [Indexed: 06/11/2023]
Abstract
We provide an extensive experimental and numerical evaluation of MQ-phase (S)M supercycles with M={3,4} of three groups of symmetry-based homonuclear dipolar recoupling rf-pulse sequences, [Formula: see text] , for establishing proximities among half-integer spin quadrupolar nuclei under moderately fast magic-angle-spinning (MAS) conditions in single-quantum-single-quantum (1Q-1Q) correlation NMR experiments. The relative merits of the (S)M schemes for variations in resonance offsets and rf-amplitude errors were assessed by numerically simulated magnetization transfers in spin-3/2 pairs with variable isotropic chemical shifts and quadrupolar coupling constants. Experimental demonstrations of 23Na (spin-3/2) NMR on Na2MoO4·2H2O and 27Al (spin-5/2) NMR on AlPO-CJ19 [(NH4)2Al4(PO4)4HPO4·H2O] are presented at 14.1 T and 24 kHz MAS. We recommend using the (SR221)3 or (SR221)4 supercycles for samples that exhibit small chemical-shift dispersions (<3 kHz), and any (SRNNN/2)3 scheme with N⩾10 for larger spreads of isotropic chemical shifts. However, because the (SRNNN/2)3 sequences recouple heteronuclear dipolar interactions, their application to proton-bearing samples requires high-power proton decoupling during the mixing period. Alternatively, the (SR241)3 and (SR241)4 schemes may be employed in the absence of proton decoupling, but with poorer compensation to resonance-offsets and rf-amplitude errors.
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Affiliation(s)
- Yang Yu
- Department of Materials and Environmental Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Philipp Keil
- Institute for Physical Chemistry, Westfälische Wilhelms-Universität Münster, DE-48 149 Münster, Germany
| | - Baltzar Stevensson
- Department of Materials and Environmental Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Michael Ryan Hansen
- Institute for Physical Chemistry, Westfälische Wilhelms-Universität Münster, DE-48 149 Münster, Germany
| | - Mattias Edén
- Department of Materials and Environmental Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden.
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5
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Kobayashi T, Wang Z, Pruski M. Homonuclear dipolar recoupling of arbitrary pairs in multi-spin systems under magic angle spinning: A double-frequency-selective ZQ-SEASHORE experiment. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2019; 101:76-81. [PMID: 31129364 DOI: 10.1016/j.ssnmr.2019.05.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 05/10/2019] [Accepted: 05/13/2019] [Indexed: 06/09/2023]
Abstract
We describe a useful method for measuring the internuclear distances within arbitrarily selected pairs of like nuclei in dipolar-coupled multi-spin systems. The method uses a combination of the zero-quantum shift-evolution-assisted selective homonuclear recoupling (ZQ-SEASHORE) technique developed by Hu and Tycko [J. Chem. Phys. 2009, 131, 045101] and double-frequency-selective radio-frequency pulse. The double-frequency-selective pulse inverts polarizations of two spins simultaneously, and thus applications of the method presented here are only limited by the spectral resolution, and not by the number of interacting spins. Our experiments demonstrate the validity of the method and present analytical expressions for the dephasing curve.
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Affiliation(s)
- Takeshi Kobayashi
- U.S. DOE Ames Laboratory, Iowa State University, Ames, IA, 50011-3020, United States.
| | - 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
| | - 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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Zhang Z, Liu H, Deng J, Tycko R, Yang J. Optimization of band-selective homonuclear dipolar recoupling in solid-state NMR by a numerical phase search. J Chem Phys 2019; 150:154201. [PMID: 31005077 DOI: 10.1063/1.5092986] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Spin polarization transfers among aliphatic 13C nuclei, especially 13Cα-13Cβ transfers, permit correlations of their nuclear magnetic resonance (NMR) frequencies that are essential for signal assignments in multidimensional solid-state NMR of proteins. We derive and demonstrate a new radio-frequency (RF) excitation sequence for homonuclear dipolar recoupling that enhances spin polarization transfers among aliphatic 13C nuclei at moderate magic-angle spinning (MAS) frequencies. The phase-optimized recoupling sequence with five π pulses per MAS rotation period (denoted as PR5) is derived initially from systematic numerical simulations in which only the RF phases are varied. Subsequent theoretical analysis by average Hamiltonian theory explains the favorable properties of numerically optimized phase schemes. The high efficiency of spin polarization transfers in simulations is preserved in experiments, in part because the RF field amplitude in PR5 is only 2.5 times the MAS frequency so that relatively low 1H decoupling powers are required. Experiments on a microcrystalline sample of the β1 immunoglobulin binding domain of protein G demonstrate an average enhancement factor of 1.6 for 13Cα → 13Cβ polarization transfers, compared to the standard 13C-13C spin-diffusion method, implying a two-fold time saving in relevant 2D and 3D experiments.
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Affiliation(s)
- Zhengfeng Zhang
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China
| | - Hui Liu
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China
| | - Jing Deng
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China
| | - Robert Tycko
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0520, USA
| | - Jun Yang
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China
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Duan P, Schmidt-Rohr K. Quick, selective NMR spectra of COH moieties in 13C-enriched solids. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 301:80-84. [PMID: 30852301 DOI: 10.1016/j.jmr.2019.02.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 02/21/2019] [Accepted: 02/26/2019] [Indexed: 06/09/2023]
Abstract
A convenient one-dimensional magic-angle spinning NMR method is presented that provides selective NMR spectra of COH moieties in uniformly 13C-enriched organic materials. This method, termed hydroxyl-proton selection (HOPS), eliminates the magnetization of protons directly bonded to carbons by recoupling the 1H-13C dipolar interaction for a short time (∼70 μs), which also serves as a chemical-shift filter to suppress 1H magnetization of CH3 groups. After cross polarization to 13C, the signals of COH and COOH carbons are observed selectively. This makes it possible to distinguish alcohols from ethers, in particular phenols from aromatic ethers such as the furans often formed by dehydration of glucose, and carboxylic acids from carboxylates and ethers. HOPS NMR reveals that orthodiphenols are often a major component of low-temperature carbon materials. For instance, it forces the reassignment of the 143 ppm 13C NMR signal of hydrothermal carbon to such catecholic diphenols, while a previous NMR-based structural model had attributed this peak to a central furan-furan linkage.
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Affiliation(s)
- Pu Duan
- Department of Chemistry, Brandeis University, Waltham, MA 02453, United States
| | - Klaus Schmidt-Rohr
- Department of Chemistry, Brandeis University, Waltham, MA 02453, United States.
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8
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Khaneja N, Kumar A. Two pulse recoupling. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 281:162-171. [PMID: 28618387 DOI: 10.1016/j.jmr.2017.06.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 06/02/2017] [Accepted: 06/03/2017] [Indexed: 06/07/2023]
Abstract
The paper describes a family of novel recoupling pulse sequences in magic angle spinning (MAS) solid state NMR, called two pulse recoupling. 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 (π)ϕ(π)-ϕ where ϕ=π4n, and n is number of blocks in a rotor period. The recoupling block is made robust to rf-inhomogeneity by extending it to (π)ϕ(π)-ϕ(π)π+ϕ(π)π-ϕ. The heteronuclear recoupling pulse sequence consists of a building block [Formula: see text] and [Formula: see text] on channel I and S, where ϕ1=3π8n,ϕ2=π8n and n is number of blocks in a rotor period. The recoupling block is made robust to rf-inhomogeneity by extending it to [Formula: see text] and [Formula: see text] on two channels respectively. The recoupling pulse sequences mix the z magnetization. Experimental quantification of this method is shown for13Cα-13CO homonuclear recoupling in a sample of Glycine and 15N-13Cα heteronuclear recoupling in Alanine. Application of this method is demonstrated on a sample of tripeptide N-formyl-[U-13C,15N]-Met-Leu-Phe-OH (MLF). Compared to R-sequences (Levitt, 2002), these sequences are more robust to rf-inhomogeneity and give better sensitivity, as shown in Fig. 3.
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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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9
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Courtney JM, Rienstra CM. Efficient dipolar double quantum filtering under magic angle spinning without a (1)H decoupling field. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 269:152-156. [PMID: 27314744 PMCID: PMC5019030 DOI: 10.1016/j.jmr.2016.05.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 05/20/2016] [Accepted: 05/24/2016] [Indexed: 05/13/2023]
Abstract
We present a systematic study of dipolar double quantum (DQ) filtering in (13)C-labeled organic solids over a range of magic-angle spinning rates, using the SPC-n recoupling sequence element with a range of n symmetry values from 3 to 11. We find that efficient recoupling can be achieved for values n⩾7, provided that the (13)C nutation frequency is on the order of 100kHz or greater. The decoupling-field dependence was investigated and explicit heteronuclear decoupling interference conditions identified. The major determinant of DQ filtering efficiency is the decoupling interference between (13)C and (1)H fields. For (13)C nutation frequencies greater than 75kHz, optimal performance is observed without an applied (1)H field. At spinning rates exceeding 20kHz, symmetry conditions as low as n=3 were found to perform adequately.
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Affiliation(s)
- Joseph M Courtney
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Chad M Rienstra
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
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10
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Teymoori G, Pahari B, Edén M. Low-power broadband homonuclear dipolar recoupling in MAS NMR by two-fold symmetry pulse schemes for magnetization transfers and double-quantum excitation. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2015; 261:205-20. [PMID: 26515279 DOI: 10.1016/j.jmr.2015.09.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 08/31/2015] [Accepted: 09/07/2015] [Indexed: 05/28/2023]
Abstract
We provide an experimental, numerical, and high-order average Hamiltonian evaluation of an open-ended series of homonuclear dipolar recoupling sequences, SR [Formula: see text] with p=1,2,3,…. While operating at a very low radio-frequency (rf) power, corresponding to a nutation frequency of 1/2 of the magic-angle spinning (MAS) rate (ωnut=ωr/2), these recursively generated double-quantum (2Q) dipolar recoupling schemes offer a progressively improved compensation to resonance offsets and rf inhomogeneity for increasing pulse-sequence order p. The excellent recoupling robustness to these experimental obstacles, as well as to CSA, is demonstrated for 2Q filtering (2QF) experiments and for driving magnetization transfers in 2D NMR correlation spectroscopy, where the sequences may provide either double or zero quantum dipolar Hamiltonians during mixing. Experimental and numerical demonstrations, which mostly target conditions of "ultra-fast" MAS (≳50kHz) and high magnetic fields, are provided for recoupling of (13)C across a wide range of isotropic and anisotropic chemical shifts, as well as dipolar coupling constants, encompassing [2,3-(13)C2]alanine, [1,3-(13)C2]alanine, diammonium [1,4-(13)C2]fumarate, and [U-(13)C]tyrosine. When compared at equal power levels, a superior performance is observed for the SR [Formula: see text] sequences with p⩾3 relative to existing and well-established 2Q recoupling techniques. At ultra-fast MAS, proton decoupling is redundant during the homonuclear dipolar recoupling of dilute spins in organic solids, which renders the family of SR [Formula: see text] schemes the first efficient 2Q recoupling option for general applications, such as 2Q-1Q correlation NMR and high-order multiple-quantum excitation, under truly low-power rf conditions.
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Affiliation(s)
- Gholamhasan Teymoori
- Physical Chemistry Division, Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Bholanath Pahari
- Physical Chemistry Division, Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Mattias Edén
- Physical Chemistry Division, Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden.
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Ren J, Eckert H. Measurement of homonuclear magnetic dipole-dipole interactions in multiple 1/2-spin systems using constant-time DQ-DRENAR NMR. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2015; 260:46-53. [PMID: 26397219 DOI: 10.1016/j.jmr.2015.08.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 08/22/2015] [Accepted: 08/28/2015] [Indexed: 06/05/2023]
Abstract
A new pulse sequence entitled DQ-DRENAR (Double-Quantum based Dipolar Recoupling Effects Nuclear Alignment Reduction) was recently described for the quantitative measurement of magnetic dipole-dipole interactions in homonuclear spin-1/2 systems involving multiple nuclei. As described in the present manuscript, the efficiency and performance of this sequence can be significantly improved, if the measurement is done in the constant-time mode. We describe both the theoretical analysis of this method and its experimental validation of a number of crystalline model compounds, considering both symmetry-based and back-to-back (BABA) DQ-coherence excitation schemes. Based on the combination of theoretical analysis and experimental results we discuss the effect of experimental parameters such as the chemical shift anisotropy (CSA), the spinning rate, and the radio frequency field inhomogeneity upon its performance. Our results indicate that constant-time (CT-) DRENAR is a method of high efficiency and accuracy for compounds with multiple homonuclear spin systems with particular promise for the analysis of stronger-coupled and short T2 spin systems.
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Affiliation(s)
- Jinjun Ren
- Key Laboratory of Materials for High-Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China.
| | - Hellmut Eckert
- Institut für Physikalische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstr. 30, D-48149 Münster, Germany; Instituto de Física de São Carlos, Universidade de São Paulo (USP), C.P. 369, CEP 13560-970, São Carlos, SP, Brazil.
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Ren J, Eckert H. Applications of DQ-DRENAR for the structural analysis of phosphate glasses. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2015; 72:140-147. [PMID: 26499362 DOI: 10.1016/j.ssnmr.2015.10.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A new solid state NMR technique entitled DQ-DRENAR (Double-Quantum based Dipolar Recoupling Effects Nuclear Alignment Reduction) has been recently described for measuring homonuclear dipole-dipole interactions in multi-spin-1/2 systems under magic-angle spinning conditions. As in rotational echo double resonance (REDOR), the homonuclear dipole-dipole coupling constant can be extracted from a plot of a normalized difference signal (S0-S')/S0 versus dipolar mixing time, where S is the signal amplitude with the DQ-Hamiltonian present, and S0 is the signal amplitude in the absence of the DQ-Hamiltonian, which is used for normalization. Within the range of (S0-S)/S0≤0.3-0.5 such "homonuclear REDOR curves" can be approximated by simple parabolae, yielding effective squared dipole-dipole coupling constants ∑bjk(2) summed over all the pairwise interactions present. The effect of glassy disorder has been studied by simulations, replacing singular-valued internuclear distances by Gaussian distance distributions with the same central value. This situation results in a systematic over-estimation effect, which tends to compensate the implicit under-estimation effect caused by the parabolic fitting approach. The present contribution describes applications to a number of phosphate-based glasses and glass ceramics. The method turns out to be well suited for the differentiation of the various Q((n)) phosphate species, for characterizing the spatial distribution of isolated orthophosphate ions and for the detection of incipient nano-segregation and/or phase separation effects in glass ceramics.
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Affiliation(s)
- Jinjun Ren
- Institut für Physikalische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 30, D-48149 Münster, Germany; Key Laboratory of Materials for High-Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China.
| | - Hellmut Eckert
- Institut für Physikalische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 30, D-48149 Münster, Germany; Instituto de Física de São Carlos, Universidade de São Paulo (USP), C.P. 369, CEP 13566-590 São Carlos, SP, Brazil.
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13
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Ren J, Eckert H. DQ-DRENAR with back-to-back (BABA) excitation: Measuring homonuclear dipole-dipole interactions in multiple spin-1/2 systems. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2015; 71:11-18. [PMID: 26483328 DOI: 10.1016/j.ssnmr.2015.10.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A new pulse sequence entitled DQ-DRENAR, (Double-Quantum based Dipolar Recoupling Effects Nuclear Alignment Reduction) was recently described for the quantitative measurement of magnetic dipole-dipole interactions in homonuclear spin-1/2 systems involving multiple nuclei. The double quantum coherences were created via a windowless symmetry-based pulse sequence (POST-C7). The present contribution evaluates the performance of the "Back-to-Back" excitation pulse scheme BABA-xy16 in such DRENAR experiments. Using SIMPSON simulations, special attention is given to finite pulse length effects, dipolar truncation, and chemical shift anisotropy interference. Experimental results on model compounds demonstrate good stability up to long mixing times (>10 ms) as well as high accuracy. As its dipolar coupling efficiency is relatively high (the dipolar coupling scaling factor is 4.24 times as high as that of POST-C7), DQ-DRENAR-BABA-xy16 is most appropriate for the measurement of relatively weak dipolar coupling strengths (<400 Hz). Different from POST-C7, for which the spinning rate is limited to 1/7 of the nutation frequency, DQ-DRENAR-BABA-xy16 experiments can take full advantage of ultrafast MAS experiments.
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Affiliation(s)
- Jinjun Ren
- Key Laboratory of Materials for High-Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China.
| | - Hellmut Eckert
- Institut für Physikalische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstr. 30, D-48149 Münster, Germany; Instituto de Física de São Carlos, Universidade de São Paulo (USP), C.P. 369, CEP 13560-970, São Carlos, SP, Brazil.
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14
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Teymoori G, Pahari B, Viswanathan E, Edén M. Multiple-quantum spin counting in magic-angle-spinning NMR via low-power symmetry-based dipolar recoupling. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2013; 236:31-40. [PMID: 24044967 DOI: 10.1016/j.jmr.2013.08.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 08/05/2013] [Accepted: 08/14/2013] [Indexed: 06/02/2023]
Abstract
By using a symmetry-based R2(8)(1)R2(8)(-1) double-quantum (2Q) dipolar recoupling sequence, we demonstrate high-order multiple-quantum coherence (MQC) excitation at fast magic-angle spinning (MAS) frequencies up to 34 kHz. This scheme combines several attractive features, such as a relatively high dipolar scaling factor, good compensation to rf-errors, isotropic and anisotropic chemical shifts, as well as an ultra-low radio-frequency (rf) power requirement. The latter translates into nutation frequencies below 30 kHz for MAS rates up to 60 kHz, thereby permitting rf application for very long excitation periods without risk of damaging the NMR probehead or sample, while the compensation to chemical shifts improves as the MAS rate increases. (31)P MQC spin counting is demonstrated on powders of calcium hydroxyapatite (Ca5(PO4)3OH) and anhydrous sodium diphosphate (Na4P2O7), from which all even coherence orders up to 30 and 14 were detected, respectively, over the respective MAS ranges of 15-24 kHz and 20-34 kHz. The amplitude distributions among the (31)P MQC orders depend on the precise nutation frequency during recoupling, despite that the highest detected order was relatively insensitive to this parameter. An observed gradual transition from a Gaussian to exponential functionality of the MQC amplitude-profile is discussed in relation to the prevailing approach to derive spin-cluster sizes by fitting the MQC amplitude-distribution to a Gaussian decay, where minor systematic deviations between the model and experimental data are frequently reported.
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Affiliation(s)
- Gholamhasan Teymoori
- Physical Chemistry Division, Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
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15
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Cegelski L. REDOR NMR for drug discovery. Bioorg Med Chem Lett 2013; 23:5767-75. [PMID: 24035486 PMCID: PMC4038398 DOI: 10.1016/j.bmcl.2013.08.064] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2013] [Revised: 08/12/2013] [Accepted: 08/14/2013] [Indexed: 11/19/2022]
Abstract
Rotational-echo double-resonance (REDOR) NMR is a powerful and versatile solid-state NMR measurement that has been recruited to elucidate drug modes of action and to drive the design of new therapeutics. REDOR has been implemented to examine composition, structure, and dynamics in diverse macromolecular and whole-cell systems, including taxol-bound microtubules, enzyme-cofactor-inhibitor ternary complexes, and antibiotic-whole-cell complexes. The REDOR approach involves the integrated design of specific isotopic labeling strategies and the selection of appropriate REDOR experiments. By way of example, this digest illustrates the versatility of the REDOR approach, with an emphasis on the practical considerations of experimental design and data interpretation.
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Affiliation(s)
- Lynette Cegelski
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA.
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16
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Pope A, Eilers M, Reeves PJ, Smith SO. Amino acid conservation and interactions in rhodopsin: probing receptor activation by NMR spectroscopy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1837:683-93. [PMID: 24183693 DOI: 10.1016/j.bbabio.2013.10.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 10/15/2013] [Accepted: 10/18/2013] [Indexed: 11/30/2022]
Abstract
Rhodopsin is a classical two-state G protein-coupled receptor (GPCR). In the dark, its 11-cis retinal chromophore serves as an inverse agonist to lock the receptor in an inactive state. Retinal-protein and protein-protein interactions have evolved to reduce the basal activity of the receptor in order to achieve low dark noise in the visual system. In contrast, absorption of light triggers rapid isomerization of the retinal, which drives the conversion of the receptor to a fully active conformation. Several specific protein-protein interactions have evolved that maintain the lifetime of the active state in order to increase the sensitivity of this receptor for dim-light vision in vertebrates. In this article, we review the molecular interactions that stabilize rhodopsin in the dark-state and describe the use of solid-state NMR spectroscopy for probing the structural changes that occur upon light-activation. Amino acid conservation provides a guide for those interactions that are common in the class A GPCRs as well as those that are unique to the visual system. This article is part of a Special Issue entitled: Retinal Proteins - You can teach an old dog new tricks.
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Affiliation(s)
- Andreyah Pope
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Markus Eilers
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Philip J Reeves
- School of Biological Sciences, University of Essex, Wivenhoe Park, Essex CO4 3SQ, UK
| | - Steven O Smith
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA.
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17
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Comellas G, Rienstra CM. Protein Structure Determination by Magic-Angle Spinning Solid-State NMR, and Insights into the Formation, Structure, and Stability of Amyloid Fibrils. Annu Rev Biophys 2013; 42:515-36. [DOI: 10.1146/annurev-biophys-083012-130356] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | - Chad M. Rienstra
- Center for Biophysics and Computational Biology,
- Department of Chemistry, and
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801; ,
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18
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Ren J, Eckert H. DQ-DRENAR: A new NMR technique to measure site-resolved magnetic dipole-dipole interactions in multispin-1/2 systems: Theory and validation on crystalline phosphates. J Chem Phys 2013; 138:164201. [DOI: 10.1063/1.4801634] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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19
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Progress in development and application of solid-state NMR for solid acid catalysis. CHINESE JOURNAL OF CATALYSIS 2013. [DOI: 10.1016/s1872-2067(12)60528-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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20
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Goncalves J, Eilers M, South K, Opefi CA, Laissue P, Reeves PJ, Smith SO. Magic angle spinning nuclear magnetic resonance spectroscopy of G protein-coupled receptors. Methods Enzymol 2013; 522:365-89. [PMID: 23374193 DOI: 10.1016/b978-0-12-407865-9.00017-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/08/2022]
Abstract
G protein-coupled receptors (GPCRs) represent the largest family of membrane receptors and mediate a diversity of cellular processes. These receptors have a common seven-transmembrane helix structure, yet have evolved to respond to literally thousands of different ligands. In this chapter, we describe the use of magic angle spinning solid-state NMR spectroscopy for characterizing the structure and dynamics of GPCRs. Solid-state NMR spectroscopy is well suited for structural measurements in both detergent micelles and membrane bilayer environments. We first outline the methods for large-scale production of stable, functional receptors containing (13)C- and (15)N-labeled amino acids. The expression methods make use of eukaryotic HEK293S cell lines that produce correctly folded, fully functional receptors. We subsequently describe the basic methods used for magic angle spinning solid-state NMR measurements of chemical shifts and dipolar couplings, which reveal detailed information on GPCR structure and dynamics.
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Affiliation(s)
- Joseph Goncalves
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, USA
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21
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Ren J, Eckert H. Eine homonukleare Rotationsecho-Doppelresonanzmethode zur Messung aufgelöster Abstandsverteilungen inI=1/2-Spinpaaren, -Spinclustern und -Vielspinsystemen. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201207094] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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22
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Ren J, Eckert H. A Homonuclear Rotational Echo Double-Resonance Method for Measuring Site-Resolved Distance Distributions in I=1/2 Spin Pairs, Clusters, and Multispin Systems. Angew Chem Int Ed Engl 2012; 51:12888-91. [DOI: 10.1002/anie.201207094] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2012] [Indexed: 11/05/2022]
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23
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Low-power broadband homonuclear dipolar recoupling without decoupling: Double-quantum 13C NMR correlations at very fast magic-angle spinning. Chem Phys Lett 2012. [DOI: 10.1016/j.cplett.2012.07.053] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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24
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De Paëpe G. Dipolar Recoupling in Magic Angle Spinning Solid-State Nuclear Magnetic Resonance. Annu Rev Phys Chem 2012; 63:661-84. [DOI: 10.1146/annurev-physchem-032511-143726] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Gaël De Paëpe
- Service de Chimie Inorganique et Biologique, UMR-E 3 CEA/UJF-Grenoble 1, Institut Nanosciences et Cryogénie, F-38054 Grenoble, France;
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25
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26
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Köneke SG, van Beek JD, Ernst M, Meier BH. Characteristics of zero-quantum correlation spectroscopy in MAS NMR experiments. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2010; 207:197-205. [PMID: 20920869 DOI: 10.1016/j.jmr.2010.08.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2010] [Revised: 08/29/2010] [Accepted: 08/31/2010] [Indexed: 05/29/2023]
Abstract
Zero-quantum coherence generation and reconversion in magic-angle spinning solid-state NMR is analyzed. Two methods are discussed based on implementations using symmetry-based pulse sequences that utilize either isotropic J couplings or dipolar couplings. In either case, the decoupling of abundant proton spins plays a crucial role for the efficiency of the zero-quantum generation. We present optimized sequences for measuring zero-quantum single-quantum correlation spectra in solids, achieving an efficiency of 50% in ubiquitin. The advantages and disadvantages of zero-quantum single-quantum over single-quantum single-quantum correlation spectroscopy are explored, and similarities and differences with double-quantum single-quantum correlation spectroscopy are discussed. Finally, possible application of zero-quantum single-quantum experiments to polypeptides, where it can lead to better spectral resolution is investigated using ubiquitin, where we find high efficiency and high selectivity, but also increased line widths in the MQ dimension.
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Affiliation(s)
- Stephanie G Köneke
- ETH Zürich, Physical Chemistry, Wolfgang-Pauli-Strasse 10, 8093 Zürich, Switzerland
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27
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Straasø LA, Nielsen NC. Recoupling of native homonuclear dipolar couplings in magic-angle-spinning solid-state NMR by the double-oscillating field technique. J Chem Phys 2010; 133:064501. [DOI: 10.1063/1.3464334] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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28
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Goncalves JA, Ahuja S, Erfani S, Eilers M, Smith SO. Structure and function of G protein-coupled receptors using NMR spectroscopy. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2010; 57:159-80. [PMID: 20633362 PMCID: PMC2907352 DOI: 10.1016/j.pnmrs.2010.04.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2010] [Accepted: 04/08/2010] [Indexed: 05/15/2023]
Affiliation(s)
- Joseph A Goncalves
- Department of Biochemistry and Cell Biology, Center for Structural Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
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29
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Ladizhansky V. Homonuclear dipolar recoupling techniques for structure determination in uniformly 13C-labeled proteins. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2009; 36:119-128. [PMID: 19729285 DOI: 10.1016/j.ssnmr.2009.07.003] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2009] [Accepted: 07/21/2009] [Indexed: 05/28/2023]
Abstract
In solid-state NMR magic angle spinning is often used to remove line broadening associated with anisotropic interactions, such as chemical shift anisotropy and dipolar couplings. Dipolar recoupling refers to sequences of pulses designed to reintroduce dipolar interactions that are otherwise averaged by magic angle spinning. One of the key applications of homonuclear (and heteronuclear) dipolar recoupling is for the purpose of protein structure determination. Recoupling experiments, originally designed for applications in spin-pair labeled samples, have been revised in recent years for applications in samples with extensive or uniform incorporation of isotopic labels. In these samples multiple internuclear distances can in principle be probed simultaneously, but the dipolar truncation effects (i.e. attenuation of the effects of weak couplings by strong ones) circumvent such measurements. In this article we review some of the recent developments in homonuclear recoupling methods that allow overcoming this problem.
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Affiliation(s)
- Vladimir Ladizhansky
- Department of Physics, University of Guelph, 50 Stone Road East, Guelph, Ontario, Canada.
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30
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Hu B, Delevoye L, Lafon O, Trébosc J, Amoureux JP. Double-quantum NMR spectroscopy of 31P species submitted to very large CSAs. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2009; 200:178-188. [PMID: 19616980 DOI: 10.1016/j.jmr.2009.06.020] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2009] [Revised: 06/24/2009] [Accepted: 06/24/2009] [Indexed: 05/28/2023]
Abstract
We introduce an original pulse sequence, BR2(2)(1)(taupitau), which is a block super-cycled R2(2)(1) sequence employing as basic element a pi pulse sandwiched by 'window' intervals. This homonuclear dipolar recoupling method allows the efficient excitation of double-quantum coherences between spin-1/2 nuclei submitted to very large chemical shift anisotropy. We demonstrate that this technique can be employed in double-quantum<-->single-quantum (31)P homonuclear correlation experiment at high magnetic field (B(0)>or=14 T) and high MAS frequencies (nu(R)>or=30 kHz). The performances of BR2(2)(1)(taupitau) are compared to those of the double-quantum recoupling methods, such as BABA and bracketed fp-RFDR, which were already employed at fast MAS rates. The BR2(2)(1)(taupitau) sequence displays a higher robustness to CSA and offset than the other existing techniques.
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Affiliation(s)
- B Hu
- UCCS, CNRS-8181, Lille-University, Villeneuve D'Ascq, France
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31
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Edén M, Lo AYH. Supercycled symmetry-based double-quantum dipolar recoupling of quadrupolar spins in MAS NMR: I. Theory. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2009; 200:267-279. [PMID: 19648039 DOI: 10.1016/j.jmr.2009.07.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2009] [Revised: 07/04/2009] [Accepted: 07/08/2009] [Indexed: 05/28/2023]
Abstract
Using average Hamiltonian (AH) theory, we analyze recently introduced homonuclear dipolar recoupling pulse sequences for exciting central-transition double-quantum coherences (2QC) between half-integer spin quadrupolar nuclei undergoing magic-angle-spinning. Several previously observed differences among the recoupling schemes concerning their compensation to resonance offsets and radio-frequency (rf) inhomogeneity may qualitatively be rationalized by an AH analysis up to third perturbation order, despite its omission of first-order quadrupolar interactions. General aspects of the engineering of 2Q-recoupling pulse sequences applicable to half-integer spins are discussed, emphasizing the improvements offered from a diversity of supercycles providing enhanced suppression of undesirable AH cross-terms between resonance offsets and rf amplitude errors.
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Affiliation(s)
- Mattias Edén
- Physical Chemistry Division, Stockholm University, Stockholm, Sweden.
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32
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Lewandowski JR, De Paëpe G, Eddy MT, Struppe J, Maas W, Griffin RG. Proton assisted recoupling at high spinning frequencies. J Phys Chem B 2009; 113:9062-9. [PMID: 19489532 PMCID: PMC2738631 DOI: 10.1021/jp810280t] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We demonstrate the successful application of (13)C-(13)C proton assisted recoupling (PAR) on [U-(13)C,(15)N] N-f-MLF-OH and [U-(13)C,(15)N] protein GB1 at high magic angle spinning (MAS) frequencies (omega(r)/2pi = 65 kHz). Specifically, by combining PAR mixing with low power heteronuclear decoupling (omega(1H)/2pi approximately 16 kHz) and high spinning frequencies, we obtain high resolution 2D spectra displaying long-range (13)C-(13)C contacts from which distance estimates can be extracted. These experiments therefore demonstrate the possibility of performing high resolution structural studies in the limit of high spinning frequency and low power (1)H decoupling, a regime which optimizes the resolution of protein samples and preserves their integrity.
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Affiliation(s)
- Józef R. Lewandowski
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Gaël De Paëpe
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Matthew T. Eddy
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Jochem Struppe
- Bruker BioSpin Corporation, Billerica, Massachusetts 01821
| | - Werner Maas
- Bruker BioSpin Corporation, Billerica, Massachusetts 01821
| | - Robert G. Griffin
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
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33
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Bayro MJ, Huber M, Ramachandran R, Davenport TC, Meier BH, Ernst M, Griffin RG. Dipolar truncation in magic-angle spinning NMR recoupling experiments. J Chem Phys 2009; 130:114506. [PMID: 19317544 DOI: 10.1063/1.3089370] [Citation(s) in RCA: 138] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Quantitative solid-state NMR distance measurements in strongly coupled spin systems are often complicated due to the simultaneous presence of multiple noncommuting spin interactions. In the case of zeroth-order homonuclear dipolar recoupling experiments, the recoupled dipolar interaction between distant spins is attenuated by the presence of stronger couplings to nearby spins, an effect known as dipolar truncation. In this article, we quantitatively investigate the effect of dipolar truncation on the polarization-transfer efficiency of various homonuclear recoupling experiments with analytical theory, numerical simulations, and experiments. In particular, using selectively (13)C-labeled tripeptides, we compare the extent of dipolar truncation in model three-spin systems encountered in protein samples produced with uniform and alternating labeling. Our observations indicate that while the extent of dipolar truncation decreases in the absence of directly bonded nuclei, two-bond dipolar couplings can generate significant dipolar truncation of small, long-range couplings. Therefore, while alternating labeling alleviates the effects of dipolar truncation, and thus facilitates the application of recoupling experiments to large spin systems, it does not represent a complete solution to this outstanding problem.
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Affiliation(s)
- Marvin J Bayro
- Department of Chemistry, Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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34
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Mafra L, Gomes JRB, Trébosc J, Rocha J, Amoureux JP. 1H-1H double-quantum CRAMPS NMR at very-fast MAS (nuR=35 kHz): a resolution enhancement method to probe 1H-1H proximities in solids. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2009; 196:88-91. [PMID: 18977161 DOI: 10.1016/j.jmr.2008.10.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2008] [Revised: 09/30/2008] [Accepted: 10/02/2008] [Indexed: 05/27/2023]
Abstract
A High-resolution two-dimensional (2D) (1)H double-quantum (DQ) homonuclear recoupling experiments, combined with smooth amplitude-modulation (SAM) homonuclear decoupling is presented. The experiment affords highly resolved and clean (1)H DQ-SQ 2D spectra at very-fast MAS rates (nu(R)=35 kHz). The method is well suited to probe (1)H-(1)H distances in powdered solids and demonstrations are applied on a NaH(2)PO(4) powdered sample, an inorganic compound having hydrogen bonding networks.
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Affiliation(s)
- Luís Mafra
- Department of Chemistry, University of Aveiro, Campus de Santiago, CICECO, 3810-193 Aveiro, Portugal.
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35
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De Paëpe G, Lewandowski JR, Loquet A, Böckmann A, Griffin RG. Proton assisted recoupling and protein structure determination. J Chem Phys 2008; 129:245101. [PMID: 19123534 PMCID: PMC2755343 DOI: 10.1063/1.3036928] [Citation(s) in RCA: 155] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Accepted: 11/03/2008] [Indexed: 11/14/2022] Open
Abstract
We introduce a homonuclear version of third spin assisted recoupling, a second-order mechanism that can be used for polarization transfer between (13)C or (15)N spins in magic angle spinning (MAS) NMR experiments, particularly at high spinning frequencies employed in contemporary high field MAS experiments. The resulting sequence, which we refer to as proton assisted recoupling (PAR), relies on a cross-term between (1)H-(13)C (or (1)H-(15)N) couplings to mediate zero quantum (13)C-(13)C (or (15)N-(15)N recoupling). In particular, using average Hamiltonian theory we derive an effective Hamiltonian for PAR and show that the transfer is mediated by trilinear terms of the form C(1) (+/-)C(2) (-/+)H(Z) for (13)C-(13)C recoupling experiments (or N(1) (+/-)N(2) (-/+)H(Z) for (15)N-(15)N). We use analytical and numerical simulations to explain the structure of the PAR optimization maps and to delineate the PAR matching conditions. We also detail the PAR polarization transfer dependence with respect to the local molecular geometry and explain the observed reduction in dipolar truncation. Finally, we demonstrate the utility of PAR in structural studies of proteins with (13)C-(13)C spectra of uniformly (13)C, (15)N labeled microcrystalline Crh, a 85 amino acid model protein that forms a domain swapped dimer (MW=2 x 10.4 kDa). The spectra, which were acquired at high MAS frequencies (omega(r)2pi>20 kHz) and magnetic fields (750-900 MHz (1)H frequencies) using moderate rf fields, exhibit numerous cross peaks corresponding to long (up to 6-7 A) (13)C-(13)C distances which are particularly useful in protein structure determination. Using results from PAR spectra we calculate the structure of the Crh protein.
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Affiliation(s)
- Gaël De Paëpe
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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36
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Bayro MJ, Ramachandran R, Caporini MA, Eddy MT, Griffin RG. Radio frequency-driven recoupling at high magic-angle spinning frequencies: homonuclear recoupling sans heteronuclear decoupling. J Chem Phys 2008; 128:052321. [PMID: 18266438 DOI: 10.1063/1.2834736] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We describe solid-state NMR homonuclear recoupling experiments at high magic-angle spinning (MAS) frequencies using the radio frequency-driven recoupling (RFDR) scheme. The effect of heteronuclear decoupling interference during RFDR recoupling at high spinning frequencies is investigated experimentally and via numerical simulations, resulting in the identification of optimal decoupling conditions. The effects of MAS frequency, RF field amplitude, bandwidth, and chemical shift offsets are examined. Most significantly, it is shown that broadband homonuclear correlation spectra can be efficiently obtained using RFDR without decoupling during the mixing period in fully protonated samples, thus considerably reducing the rf power requirements for acquisition of (13)C-(13)C correlation spectra. The utility of RFDR sans decoupling is demonstrated with broadband correlation spectra of a peptide and a model protein at high MAS frequencies and high magnetic field.
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Affiliation(s)
- Marvin J Bayro
- Francis Bitter Magnet Laboratory and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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37
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De Paëpe G, Lewandowski JR, Griffin RG. Spin dynamics in the modulation frame: Application to homonuclear recoupling in magic angle spinning solid-state NMR. J Chem Phys 2008; 128:124503. [DOI: 10.1063/1.2834732] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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38
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Zheng Z, Qiang W, Weliky DP. Investigation of finite-pulse radiofrequency-driven recoupling methods for measurement of intercarbonyl distances in polycrystalline and membrane-associated HIV fusion peptide samples. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2007; 45 Suppl 1:S247-S260. [PMID: 18157840 DOI: 10.1002/mrc.2160] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Two finite-pulse radiofrequency-driven recoupling (RFDR) methods were compared and applied to the measurement of 3-6 Å (13)CO-(13)CO distances in polycrystalline and membrane-associated HIV fusion peptide (HFP) samples. The RFDR methods were based on π pulses and were relatively straightforward to implement and insensitive to pulse imperfections. The two tested methods were: (i) constant-time double-quantum buildup with finite pulses (fpCTDQBU) for which the pulse sequence maintained a constant transverse relaxation period while allowing a variable period of dipolar dephasing; and (ii) constant-time finite-pulse rf-driven recoupling (fpRFDR-CT) for which the duration of transverse relaxation increased with increasing dephasing period. The fpRFDR-CT method yielded higher signal-to-noise and an accurate determination of a ~5 Å intercarbonyl distance was made in a crystalline peptide which had T(2) ≈ 55 ms. In some contrast, the HFP samples had T(2) ≈ 15 ms and the fpRFDR-CT data were dominated by transverse relaxation. Examination of the fpCTDQBU sequence showed: (i) the most rapid signal buildup was obtained with application of one (13) C π pulse per rotor period rather than one (13)C π pulse per multiple rotor periods and (ii) the data were insensitive to ~15 ppm transmitter offset and to ~5° variation of π pulse nutation angle. For HFP samples which were (13)CO labeled at a single residue, analyses of the fpCTDQBU data were interpreted with a model of mixed parallel and antiparallel β-strand arrangements in the N-terminal region of HFP and loss of parallel β-sheet structure in the C-terminal region of HFP.
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Affiliation(s)
- Zhaoxiong Zheng
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
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Matsuoka S, Ikeuchi H, Umegawa Y, Matsumori N, Murata M. Membrane interaction of amphotericin B as single-length assembly examined by solid state NMR for uniformly 13C-enriched agent. Bioorg Med Chem 2006; 14:6608-14. [PMID: 16782343 DOI: 10.1016/j.bmc.2006.06.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2006] [Revised: 05/31/2006] [Accepted: 06/01/2006] [Indexed: 11/29/2022]
Abstract
The membrane interaction of amphotericin B (AmB), one of the most important anti-fungal drugs, was investigated by solid state NMR measurements of uniformly 13C-enriched AmB, which was prepared by the culture of the drug-producing microorganism in the presence of [u-13C6]glucose. All the 13C NMR signals of AmB upon binding to DLPC membrane were successfully assigned on the basis of the 13C-13C correlation spectrum. 13C-31P RDX (Rotational-Echo Double Resonance for X-clusters) experiments clearly revealed the REDOR dephasing effects for carbon atoms residing in the both terminal parts, whereas no dephasing was observed for the middle parts including polyolefinic C20-C33 and hydroxyl-bearing C8/C9 parts. These observations suggest that AmB binds to DLPC membrane with a high affinity to the phospholipid and spans the membrane with a single molecular length.
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Affiliation(s)
- Shigeru Matsuoka
- Department of Chemistry, Graduate School of Science, Osaka University, 1-16 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
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Marin-Montesinos I, Brouwer DH, Antonioli G, Lai WC, Brinkmann A, Levitt MH. Heteronuclear decoupling interference during symmetry-based homonuclear recoupling in solid-state NMR. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2005; 177:307-17. [PMID: 16169757 DOI: 10.1016/j.jmr.2005.07.020] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2005] [Revised: 07/13/2005] [Accepted: 07/14/2005] [Indexed: 05/04/2023]
Abstract
We examine the influence of continuous-wave heteronuclear decoupling on symmetry-based double-quantum homonuclear dipolar recoupling, using experimental measurements, numerical simulations, and average Hamiltonian theory. There are two distinct regimes in which the heteronuclear interference effects are minimized. The first regime utilizes a moderate homonuclear recoupling field and a strong heteronuclear decoupling field; the second regime utilizes a strong homonuclear recoupling field and a weak or absent heteronuclear decoupling field. The second regime is experimentally accessible at moderate or high magic-angle-spinning frequencies and is particularly relevant for many realistic applications of solid-state NMR recoupling experiments to organic or biological materials.
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41
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Two-dimensional solid-state NMR studies of crystalline poly(ethylene oxide): Conformations and chemical shifts. POLYMER 2005. [DOI: 10.1016/j.polymer.2005.09.035] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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42
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Kehlet C, Vosegaard T, Khaneja N, Glaser SJ, Nielsen NC. Low-power homonuclear dipolar recoupling in solid-state NMR developed using optimal control theory. Chem Phys Lett 2005. [DOI: 10.1016/j.cplett.2005.08.061] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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43
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Brinkmann A, Edén M. Second order average Hamiltonian theory of symmetry-based pulse schemes in the nuclear magnetic resonance of rotating solids: Application to triple-quantum dipolar recoupling. J Chem Phys 2004; 120:11726-45. [PMID: 15268208 DOI: 10.1063/1.1738102] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The average Hamiltonian theory (AHT) of several classes of symmetry-based radio-frequency pulse sequences is developed to second order, allowing quantitative analyses of a wide range of recoupling and decoupling applications in magic-angle-spinning solid state nuclear magnetic resonance. General closed analytical expressions are presented for a cross term between any two interactions recoupled to second order AHT. We classify them into different categories and show that some properties of the recoupling pulse sequence may be predicted directly from this classification. These results are applied to examine a novel homonuclear recoupling strategy, effecting a second order average dipolar Hamiltonian comprising trilinear triple quantum (3Q) spin operators. We discuss general features and design principles of such 3Q recoupling sequences and demonstrate by numerical simulations and experiments that they provide more efficient excitation of (13)C 3Q coherences compared to previous techniques. We passed up to 15% of the signal through a state of 3Q coherence in rotating powders of uniformly (13)C-labeled alanine and tyrosine. Second order recoupling-based (13)C homonuclear 3Q correlation spectroscopy is introduced and demonstrated on tyrosine.
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Affiliation(s)
- Andreas Brinkmann
- Physical Chemistry/Solid State NMR, NSRIM Center, University of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands
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Ladizhansky V, Griffin RG. Band-selective carbonyl to aliphatic side chain 13C-13C distance measurements in U-13C,15N-labeled solid peptides by magic angle spinning NMR. J Am Chem Soc 2004; 126:948-58. [PMID: 14733572 DOI: 10.1021/ja037138c] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We describe three-dimensional magic angle spinning NMR experiments that enable simultaneous band-selective measurement of the multiple distance constraints between carbonyl and side chain carbons in uniformly 13C,15N-labeled peptides. The approaches are designed to circumvent the dipolar truncation and to allow experimental separation of the multiple quantum (MQ) relaxation and dipolar effects. The pulse sequences employ the double quantum (DQ) rotational resonance in the tilted frame (R2TR) to perform selective polarization transfers that reintroduce the 13C'-13Cgamma,delta dipolar interactions. The scheme avoids recoupling of the strongly coupled C'-Calpha and C'-Cbeta spin pairs, therefore minimizing dipolar truncation effects. The experiment is performed in a constant time fashion as a function of the radio frequency irradiation intensity and measures the line shape of the DQ transition. The width and the intensity of this line shape are analyzed in terms of the DQ relaxation and dipolar coupling. The attenuation of the multispin effects in the presence of relaxation enables a two-spin approximation to be employed for the analysis of the experimental data. The systematic error introduced by this approximation is estimated by comparing the results with a three-spin simulation. The contributions of B1-inhomogeneity, CSA orientation effects, and the effects of inhomogeneous line broadening are also estimated. The experiments are demonstrated in model U-13C,15N-labeled peptides, N-acetyl-L-Val-L-Leu and N-formyl-L-Met-L-Leu-L-Phe, where 10 and 6 distances, ranging between 3 and 6 A, were measured, respectively.
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Affiliation(s)
- Vladimir Ladizhansky
- Department of Chemistry and Center for Magnetic Resonance, Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, USA
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Yao XL, Hong M. Structure Distribution in an Elastin-Mimetic Peptide (VPGVG)3 Investigated by Solid-State NMR. J Am Chem Soc 2004; 126:4199-210. [PMID: 15053609 DOI: 10.1021/ja036686n] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Elastin is an extracellular-matrix protein that imparts elasticity to tissues. We have used solid-state NMR to determine a number of distances and torsion angles in an elastin-mimetic peptide, (VPGVG)3, to understand the structural basis of elasticity. C-H and C-N distances between the V6 carbonyl and the V9 amide segment were measured using 13C-15N and 13C-1H rotational-echo double-resonance experiments. The results indicate the coexistence of two types of intramolecular distances: a third of the molecules have short C-H and C-N distances of 3.3 +/- 0.2 and 4.3 +/- 0.2 A, respectively, while the rest have longer distances of about 7 A. Complementing the distance constraints, we measured the (phi, psi ) torsion angles of the central pentameric unit using dipolar correlation NMR. The -angles of P7 and G8 are predominantly ~150, thus restricting the majority of the peptide to be extended. Combining all torsion angles measured for the five residues, the G8 C chemical shift, and the V6-V9 distances, we obtained a bimodal structure distribution for the PG residues in VPGVG. The minor form is a compact structure with a V6-V9 C=O-HN hydrogen bond and can be either a type II -turn or a previously unidentified turn with Pro (phi = -70, psi= 20 +/- 20) and Gly ( phi= -100 +/- 20, psi = -20 +/- 20). The major form is an extended and distorted beta-strand without a V6-V9 hydrogen bond and differs from the ideal parallel and antiparallel beta-strands. The other three residues in the VPGVG unit mainly adopt antiparallel beta-sheet torsion angles. Since (VPGVG)3 has the same 13C and 15N isotropic and anisotropic chemical shifts as the elastin-mimetic protein (VPGXG)n (X = V and K, n = 195), the observed conformational distribution around Pro and Gly sheds light on the molecular mechanism of elastin elasticity.
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Affiliation(s)
- X L Yao
- Department of Chemistry, Iowa State University, Ames, Iowa, USA
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Bjerring M, Rasmussen JT, Schultz Krogshave R, Nielsen NC. Heteronuclear coherence transfer in solid-state nuclear magnetic resonance using a γ-encoded transferred echo experiment. J Chem Phys 2003. [DOI: 10.1063/1.1613933] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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47
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Hong M, Isailovic D, McMillan RA, Conticello VP. Structure of an elastin-mimetic polypeptide by solid-state NMR chemical shift analysis. Biopolymers 2003; 70:158-68. [PMID: 14517905 DOI: 10.1002/bip.10431] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The conformation of an elastin-mimetic recombinant protein, [(VPGVG)4(VPGKG)]39, is investigated using solid-state NMR spectroscopy. The protein is extensively labeled with 13C and 15N, and two-dimensional 13C-13C and 15N-13C correlation experiments were carried out to resolve and assign the isotropic chemical shifts of the various sites. The Pro 15N, 13Calpha, and 13Cbeta isotropic shifts, and the Gly-3 Calpha isotropic and anisotropic chemical shifts support the predominance of type-II beta-turn structure at the Pro-Gly pair but reject a type-I beta-turn. The Val-1 preceding Pro adopts mostly beta-sheet torsion angles, while the Val-4 chemical shifts are intermediate between those of helix and sheet. The protein exhibits a significant conformational distribution, shown by the broad line widths of the 15N and 13C spectra. The average chemical shifts of the solid protein are similar to the values in solution, suggesting that the low-hydration polypeptide maintains the same conformation as in solution. The ability to measure these conformational restraints by solid-state NMR opens the possibility of determining the detailed structure of this class of fibrous proteins through torsion angles and distances.
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Affiliation(s)
- M Hong
- Department of Chemistry, Iowa State University, Ames, IA 50011, USA.
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48
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Iuliucci RJ, Clawson J, Hu JZ, Solum MS, Barich D, Grant DM, Taylor CMV. Ring-chain tautomerism in solid-phase erythromycin A: evidence by solid-state NMR. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2003; 24:23-38. [PMID: 12850255 DOI: 10.1016/s0926-2040(03)00029-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Chemical shift modeling, utilizing the DFT B3LYP/D95** method, provides the spectral assignment of the 35 visible 13C resonances from the solid-phase erythromycin A dihydrate. A new resonance at 110.8ppm is observed in the high-resolution 13C CP/MAS spectrum upon the application of heat or sample desiccation. With the use of the dipolar-dephasing spectral editing technique, this resonance is identified as a hemiketal carbon and the alternative hypothesis, a conformational change to the anomeric carbon of the desosamine sugar, is ruled out. Hence, the formation of a cyclic hemiketal in erythromycin A while in the solid phase is proven by solid-state NMR. The principal components of the 13C chemical-shift tensor corresponding to this hemiketal are reported. This is the first measurement of hemiketal 13C principal values. The delta11 and delta22 components are unique compared to anomeric carbon values reported in the literature.
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Affiliation(s)
- Robbie J Iuliucci
- Department of Chemistry, Washington and Jefferson College, Washington, PA 15301, USA.
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50
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Bjerring M, Vosegaard T, Malmendal A, Nielsen N. Methodological development of solid-state NMR for characterization of membrane proteins. ACTA ACUST UNITED AC 2003. [DOI: 10.1002/cmr.a.10069] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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