title: Influence of the coupling of interdomain and overall motions on NMR relaxation.
abstract: Most theoretical models for NMR relaxation in liquids assume that overall rotational motion can be described as rotational diffusion with a single diffusion tensor. Such models cannot handle motions (such as between "closed" and "open" states of an enzyme, or between conformers of a partially disordered system) where the shape of the molecule (and hence its rotational diffusion behavior) fluctuates. We provide here a formalism for dealing with such problems. The model involves jumps between discrete conformers with different overall diffusion tensors, and a master (rate) equation to describe the transitions between these conformers. Numerical examples are given for a two-site jump model where global and local motions are concerted, showing how the rate of conformational transitions (relative to the rate of rotational diffusion) affects the observed relaxation parameters.
authors.affiliation: Department of Chemistry and Chemical Biology, and BioMaPS Institute, Rutgers University, Piscataway, NJ 08854-8087, USA.
authors.forename: Vance
authors.initials: V
authors.lastname: Wong
authors.forename: David A
authors.initials: DA
authors.lastname: Case
authors.forename: Attila
authors.initials: A
authors.lastname: Szabo
mesh_terms: D004058:Diffusion; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D009038:Motion; D012399:Rotation