Microsecond Protein Dynamics from Combined Bloch-McConnell and Near-Rotary-Resonance R1p Relaxation-Dispersion MAS NMR |
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Authors: | Dr. Dominique Marion Dr. Diego F. Gauto Isabel Ayala Karine Giandoreggio-Barranco Dr. Paul Schanda |
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Affiliation: | Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale (IBS), 71 avenue des martyrs, 38000 Grenoble, France |
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Abstract: | Studying protein dynamics on microsecond-to-millisecond (μs-ms) time scales can provide important insight into protein function. In magic-angle-spinning (MAS) NMR, μs dynamics can be visualized by rotating-frame relaxation dispersion experiments in different regimes of radio-frequency field strengths: at low RF field strength, isotropic-chemical-shift fluctuation leads to “Bloch-McConnell-type” relaxation dispersion, while when the RF field approaches rotary resonance conditions bond angle fluctuations manifest as increased rate constants (“Near-Rotary-Resonance Relaxation Dispersion”, NERRD). Here we explore the joint analysis of both regimes to gain comprehensive insight into motion in terms of geometric amplitudes, chemical-shift changes, populations and exchange kinetics. We use a numerical simulation procedure to illustrate these effects and the potential of extracting exchange parameters, and apply the methodology to the study of a previously described conformational exchange process in microcrystalline ubiquitin. |
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Keywords: | Conformational exchange NERRD numerical spin simulations crystalline protein dynamics ubiquitin |
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