Relaxation par RMN multi-champs dans les biomolécules
- Authors
- Publication Date
- Jun 28, 2021
- Source
- HAL-Descartes
- Keywords
- Language
- English
- License
- Unknown
- External links
Abstract
Nuclear spin relaxation is a fundamental phenomenon in Nuclear Magnetic Resonance (NMR). During the course of an experiment, it leads to polarization losses that can be detrimental to the spectrum quality. Taking spin relaxation into account when developing NMR pulse sequences appears essential, and can reveal itself beneficial, as shown in TRansverse Optimized SpectroscopY (TROSY) type of experiments. After a brief introduction to nuclear spin relaxation theory in liquid, we will detail how it has been implemented to efficiently compute relaxation rates of arbitrary spin systems. Nuclear spin relaxation theory has been used to understand the spectrum of methyl groups in the protein Ubiquitin recorded with zero-quantum evolution at low field and signal detection at high field using a two-field NMR spectrometer. This led us to extend the methyl-TROSY theory beyond its original conditions of application. In addition, we introduced the concept of two-field TROSY which relies not only on the selection of spin quantum operators with favorable relaxation properties, but also on the proper selection of the magnetic field for chemical shift labeling while retaining high-field high-sensitivity detection. Relaxation measurements report on dynamic properties over timescales ranging from pico- to seconds and more is unique. Here, we present tools to analyze the field-dependence of relaxation rates recorded while moving the sample inside the bore of the spectrometer to extend the range of available magnetic fields. Finally, we discuss models of motions adapted to the nature of internal motions in protons. We reveal the existence of a rotamer Chemical Shift Anisotropy (CSA) dependent relaxation mechanism in aliphatic side-chains.
