Rotating Frame Relaxation for Magic Angle Spinning Solid State NMR, A Promising Tool for Characterizing Biopolymer Motion

Abstract

Magic angle spinning NMR rotating frame relaxation measurements provide a powerful experimental strategy to probe biomolecules dynamics, as is illustrated by numerous recent applications. We discuss experimental strategies for this class of experiments, with a particular focus on systems where motion-driven modulation of the chemical shift interaction is the main mechanism for relaxation. We also explore and describe common strategies for interpreting the data sets and extracting motion timescale, activation energy, and angle or order parameters from rotating frame relaxation data. Using model free analysis, and numerical simulations, including time domain treatment, we explore conditions under which it is possible to obtain accurate and precise information about the timescales of motions. Overall, with rapid technical advances in solid state NMR, there is a bright future for this class of studies.