Microsecond Protein Dynamics from Combined Bloch‐McConnell and Near‐Rotary‐Resonance R1p Relaxation‐Dispersion MAS NMR. Issue 2 (20th December 2018)

• Record Type: Journal Article
• Authors: Marion, Dominique; Gauto, Diego F.; Ayala, Isabel; Giandoreggio‐Barranco, Karine; Schanda, Paul
• Is Part Of: Chemphyschem. Volume 20:Issue 2(2019)
• Page Start: 276
• Page End: 284
• Publication Date: 2018-12-20
• Subjects: Conformational exchange -- NERRD -- numerical spin simulations -- crystalline protein dynamics -- ubiquitin; Chemistry, Physical and theoretical -- Periodicals; 541.05
• DOI: 10.1002/cphc.201800935
• Languages: English
• ISSNs: 1439-4235

Abstract

Abstract: Studying protein dynamics on microsecond‐to‐millisecond ( μ s‐ms) time scales can provide important insight into protein function. In magic‐angle‐spinning (MAS) NMR, μ s dynamics can be visualized by R 1 ρ 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 ρ 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. Abstract : Combining rotating‐frame spin‐relaxation measurements over a wide range of spin‐lock radio‐frequency fields allows determining μ s conformational exchange processes. Quantitative information can be obtained about the kinetics and thermodynamics (populations) of the exchange, as well as chemical‐shift and geometrical variations between the involved states.