Incorporation of temporally correlated internal motions into the magnetic resonance relaxation treatment while considering interference of different relaxation mechanisms

Temporally correlated internal motions are incorporated into the magnetic resonance relaxation treatment, taking into account the interference between two different mechanisms of relaxation. The joint probability density function due to two different stochastic processes responsible for spin relaxation is approximated in terms of the individual probability density functions. A parameter indicative of the degree of temporal correlation between the two processes is introduced. Such a parameter of dynamics provides a way of observing and analyzing temporally correlated internal motions in macromolecules. This is important in biomolecules such as proteins and nucleic acids where the temporally correlated internal motions play a significant role in their function. Expressions for cross-correlation spectral densities are given for some common interference mechanisms. (C) 2000 Elsevier Science B.V. All rights reserved.