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Walder BJ, Prisco NA, Paruzzo FM, Yarava JR, Chmelka BF, Emsley L. Measurement of Proton Spin Diffusivity in Hydrated Cementitious Solids. J Phys Chem Lett 2019; 10:5064-5069. [PMID: 31393127 DOI: 10.1021/acs.jpclett.9b01861] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The study of hydration and crystallization processes involving inorganic oxides is often complicated by poor long-range order and the formation of heterogeneous domains or surface layers. In solid-state NMR, 1H-1H spin diffusion analyses can provide information on spatial composition distributions, domain sizes, or miscibility in both ordered and disordered solids. Such analyses have been implemented in organic solids but crucially rely on separate measurements of the 1H spin diffusion coefficients in closely related systems. We demonstrate that an experimental NMR method, in which "holes" of well-defined dimensions are created in proton magnetization, can be applied to determine spin diffusion coefficients in cementitious solids hydrated with 17O-enriched water. We determine proton spin diffusion coefficients of 240 ± 40 nm2/s for hydrated tricalcium aluminate and 140 ± 20 nm2/s for hydrated tricalcium silicate under quasistatic conditions.
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Affiliation(s)
- Brennan J Walder
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Nathan A Prisco
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
| | - Federico M Paruzzo
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Jayasubba Reddy Yarava
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Bradley F Chmelka
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
| | - Lyndon Emsley
- Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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Kwon B, Roos M, Mandala VS, Shcherbakov AA, Hong M. Elucidating Relayed Proton Transfer through a His-Trp-His Triad of a Transmembrane Proton Channel by Solid-State NMR. J Mol Biol 2019; 431:2554-2566. [PMID: 31082440 DOI: 10.1016/j.jmb.2019.05.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 04/13/2019] [Accepted: 05/05/2019] [Indexed: 01/02/2023]
Abstract
Proton transfer through membrane-bound ion channels is mediated by both water and polar residues of proteins, but the detailed molecular mechanism is challenging to determine. The tetrameric influenza A and B virus M2 proteins form canonical proton channels that use an HxxxW motif for proton selectivity and gating. The BM2 channel also contains a second histidine (His), H27, equidistant from the gating tryptophan, which leads to a symmetric H19xxxW23xxxH27 motif. The proton-dissociation constants (pKa's) of H19 in BM2 were found to be much lower than the pKa's of H37 in AM2. To determine if the lower pKa's result from H27-facilitated proton dissociation of H19, we have now investigated a H27A mutant of BM2 using solid-state NMR. 15N NMR spectra indicate that removal of the second histidine converted the protonation and tautomeric equilibria of H19 to be similar to the H37 behavior in AM2, indicating that the peripheral H27 is indeed the origin of the low pKa's of H19 in wild-type BM2. Measured interhelical distances between W23 sidechains indicate that the pore constriction at W23 increases with the H19 tetrad charge but is independent of the H27A mutation. These results indicate that H27 both accelerates proton dissociation from H19 to increase the inward proton conductance and causes the small reverse conductance of BM2. The proton relay between H19 and H27 is likely mediated by the intervening gating tryptophan through cation-π interactions. This relayed proton transfer may exist in other ion channels and has implications for the design of imidazole-based synthetic proton channels.
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Affiliation(s)
- Byungsu Kwon
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139, USA
| | - Matthias Roos
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139, USA
| | - Venkata S Mandala
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139, USA
| | - Alexander A Shcherbakov
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139, USA
| | - Mei Hong
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139, USA.
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Roos M, Wang T, Shcherbakov AA, Hong M. Fast Magic-Angle-Spinning 19F Spin Exchange NMR for Determining Nanometer 19F- 19F Distances in Proteins and Pharmaceutical Compounds. J Phys Chem B 2018; 122:2900-2911. [PMID: 29486126 PMCID: PMC6312665 DOI: 10.1021/acs.jpcb.8b00310] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Internuclear distances measured using NMR provide crucial constraints of three-dimensional structures but are often restricted to about 5 Å due to the weakness of nuclear-spin dipolar couplings. For studying macromolecular assemblies in biology and materials science, distance constraints beyond 1 nm will be extremely valuable. Here we present an extensive and quantitative analysis of the feasibility of 19F spin exchange NMR for precise and robust measurements of interatomic distances up to 1.6 nm at a magnetic field of 14.1 T, under 20-40 kHz magic-angle spinning (MAS). The measured distances are comparable to those achievable from paramagnetic relaxation enhancement but have higher precision, which is better than ±1 Å for short distances and ±2 Å for long distances. For 19F spins with the same isotropic chemical shift but different anisotropic chemical shifts, intermediate MAS frequencies of 15-25 kHz without 1H irradiation accelerate spin exchange. For spectrally resolved 19F-19F spin exchange, 1H-19F dipolar recoupling significantly speeds up 19F-19F spin exchange. On the basis of data from five fluorinated synthetic, pharmaceutical, and biological compounds, we obtained two general curves for spin exchange between CF groups and between CF3 and CF groups. These curves allow 19F-19F distances to be extracted from the measured spin exchange rates after taking into account 19F chemical shifts. These results demonstrate the robustness of 19F spin exchange NMR for distance measurements in a wide range of biological and chemical systems.
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Affiliation(s)
- Matthias Roos
- Department of Chemistry , Massachusetts Institute of Technology , 170 Albany Street , Cambridge , Massachusetts 02139 , United States
| | - Tuo Wang
- Department of Chemistry , Massachusetts Institute of Technology , 170 Albany Street , Cambridge , Massachusetts 02139 , United States
| | - Alexander A Shcherbakov
- Department of Chemistry , Massachusetts Institute of Technology , 170 Albany Street , Cambridge , Massachusetts 02139 , United States
| | - Mei Hong
- Department of Chemistry , Massachusetts Institute of Technology , 170 Albany Street , Cambridge , Massachusetts 02139 , United States
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Schneider H, Saalwächter K, Roos M. Complex Morphology of the Intermediate Phase in Block Copolymers and Semicrystalline Polymers As Revealed by 1H NMR Spin Diffusion Experiments. Macromolecules 2017. [DOI: 10.1021/acs.macromol.7b00703] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Horst Schneider
- Institut für Physik - NMR, Martin-Luther-Universität Halle-Wittenberg, Betty-Heimann-Str. 7, 06120 Halle (Saale), Germany
| | - Kay Saalwächter
- Institut für Physik - NMR, Martin-Luther-Universität Halle-Wittenberg, Betty-Heimann-Str. 7, 06120 Halle (Saale), Germany
| | - Matthias Roos
- Institut für Physik - NMR, Martin-Luther-Universität Halle-Wittenberg, Betty-Heimann-Str. 7, 06120 Halle (Saale), Germany
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany St, Cambridge, Massachusetts 02139-4208, United States
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Sorte EG, Alam TM. 1 H- 19 F REDOR-filtered NMR spin diffusion measurements of domain size in heterogeneous polymers. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2017; 55:1006-1014. [PMID: 28577309 DOI: 10.1002/mrc.4623] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Revised: 05/24/2017] [Accepted: 05/31/2017] [Indexed: 06/07/2023]
Abstract
Solid state NMR spectroscopy is inherently sensitive to chemical structure and composition and thus makes an ideal method to probe the heterogeneity of multicomponent polymers. Specifically, NMR spin diffusion experiments can be used to extract reliable information about spatial domain sizes on multiple length scales, provided that magnetization selection of one domain can be achieved. In this paper, we demonstrate the preferential filtering of protons in fluorinated domains during NMR spin diffusion experiments using 1 H-19 F heteronuclear dipolar dephasing based on rotational echo double resonance (REDOR) MAS NMR techniques. Three pulse sequence variations are demonstrated based on the different nuclei detected: direct 1 H detection, plus both 1 H➔13 C cross polarization and 1 H➔19 F cross polarization detection schemes. This 1 H-19 F REDOR-filtered spin diffusion method was used to measure fluorinated domain sizes for a complex polymer blend. The efficacy of the REDOR-based spin filter does not rely on spin relaxation behavior or chemical shift differences and thus is applicable for performing NMR spin diffusion experiments in samples where traditional magnetization filters may prove unsuccessful. This REDOR-filtered NMR spin diffusion method can also be extended to other samples where a heteronuclear spin pair exists that is unique to the domain of interest.
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Affiliation(s)
- Eric G Sorte
- Department of Organic Material Science, Sandia National Laboratories, Albuquerque, NM, 87185, USA
| | - Todd M Alam
- Department of Organic Material Science, Sandia National Laboratories, Albuquerque, NM, 87185, USA
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Schäler K, Roos M, Micke P, Golitsyn Y, Seidlitz A, Thurn-Albrecht T, Schneider H, Hempel G, Saalwächter K. Basic principles of static proton low-resolution spin diffusion NMR in nanophase-separated materials with mobility contrast. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2015; 72:50-63. [PMID: 26404771 DOI: 10.1016/j.ssnmr.2015.09.001] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 08/28/2015] [Accepted: 09/01/2015] [Indexed: 06/05/2023]
Abstract
We review basic principles of low-resolution proton NMR spin diffusion experiments, relying on mobility differences in nm-sized phases of inhomogeneous organic materials such as block-co- or semicrystalline polymers. They are of use for estimates of domain sizes and insights into nanometric dynamic inhomogeneities. Experimental procedures and limitations of mobility-based signal decomposition/filtering prior to spin diffusion are addressed on the example of as yet unpublished data on semicrystalline poly(ϵ-caprolactone), PCL. Specifically, we discuss technical aspects of the quantitative, dead-time free detection of rigid-domain signals by aid of the magic-sandwich echo (MSE), and magic-and-polarization-echo (MAPE) and double-quantum (DQ) magnetization filters to select rigid and mobile components, respectively. Such filters are of general use in reliable fitting approaches for phase composition determinations. Spin diffusion studies at low field using benchtop instruments are challenged by rather short (1)H T1 relaxation times, which calls for simulation-based analyses. Applying these, in combination with domain sizes as determined by small-angle X-ray scattering, we have determined spin diffusion coefficients D for PCL (0.34, 0.19 and 0.032nm(2)/ms for crystalline, interphase and amorphous parts, respectively). We further address thermal-history effects related to secondary crystallization. Finally, the state of knowledge concerning the connection between D values determined locally at the atomic level, using (13)C detection and CP- or REDOR-based "(1)H hole burning" procedures, and those obtained by calibration experiments, is summarized. Specifically, the non-trivial dependence of D on the magic-angle spinning (MAS) frequency, with a minimum under static and a local maximum under moderate-MAS conditions, is highlighted.
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Affiliation(s)
- Kerstin Schäler
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06099 Halle, Germany
| | - Matthias Roos
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06099 Halle, Germany
| | - Peter Micke
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06099 Halle, Germany
| | - Yury Golitsyn
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06099 Halle, Germany
| | - Anne Seidlitz
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06099 Halle, Germany
| | - Thomas Thurn-Albrecht
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06099 Halle, Germany
| | - Horst Schneider
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06099 Halle, Germany
| | - Günter Hempel
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06099 Halle, Germany
| | - Kay Saalwächter
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06099 Halle, Germany.
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Roos M, Micke P, Saalwächter K, Hempel G. Moderate MAS enhances local (1)H spin exchange and spin diffusion. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2015; 260:28-37. [PMID: 26397218 DOI: 10.1016/j.jmr.2015.08.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 08/13/2015] [Accepted: 08/28/2015] [Indexed: 05/17/2023]
Abstract
Proton NMR spin-diffusion experiments are often combined with magic-angle spinning (MAS) to achieve higher spectral resolution of solid samples. Here we show that local proton spin diffusion can indeed become faster at low (<10 kHz) spinning rates as compared to static conditions. Spin diffusion under static conditions can thus be slower than the often referred value of 0.8 nm(2)/ms, which was determined using slow MAS (Clauss et al., 1993). The enhancement of spin diffusion by slow MAS relies on the modulation of the orientation-dependent dipolar couplings during sample rotation and goes along with transient level crossings in combination with dipolar truncation. The experimental finding and its explanation is supported by density matrix simulations, and also emphasizes the sensitivity of spin diffusion to the local coupling topology. The amplification of spin diffusion by slow MAS cannot be explained by any model based on independent spin pairs; at least three spins have to be considered.
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Affiliation(s)
- Matthias Roos
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, Betty-Heimann-Str. 7, 06120 Halle (Saale), Germany.
| | - Peter Micke
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, Betty-Heimann-Str. 7, 06120 Halle (Saale), Germany
| | - Kay Saalwächter
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, Betty-Heimann-Str. 7, 06120 Halle (Saale), Germany
| | - Günter Hempel
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, Betty-Heimann-Str. 7, 06120 Halle (Saale), Germany.
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Demers JP, Vijayan V, Lange A. Recovery of Bulk Proton Magnetization and Sensitivity Enhancement in Ultrafast Magic-Angle Spinning Solid-State NMR. J Phys Chem B 2015; 119:2908-20. [DOI: 10.1021/jp511987y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Jean-Philippe Demers
- Department of NMR-Based Structural
Biology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Vinesh Vijayan
- Department of NMR-Based Structural
Biology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Adam Lange
- Department of NMR-Based Structural
Biology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
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Meyer HW, Schneider H, Saalwächter K. Proton NMR spin-diffusion studies of PS-PB block copolymers at low field: two- vs three-phase model and recalibration of spin-diffusion coefficients. Polym J 2012. [DOI: 10.1038/pj.2012.88] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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