Microsecond Protein Dynamics from Combined Bloch-McConnell and Near-Rotary-Resonance R1p Relaxation-Dispersion MAS NMR.

ABSTRACT: Studying protein dynamics on microsecond-to-millisecond (?s-ms) time scales can provide important insight into protein function. In magic-angle-spinning (MAS) NMR, ?s dynamics can be visualized by R 1 ? 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 R 1 ? 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.

SUBMITTER: Marion D 

PROVIDER: S-EPMC6354937 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature