Dynamics of macromolecule spin-labelled side-chain groups by electron paramagnetic resonance spectra simulation

Abstract

A new approach to simulating and deciphering experimental EPR spectra of spin-labelled macromolecules is herein described. This approach is based on the fact that every EPR spectrum corresponds to the existing stationary stochastic process of angular reorientations of the aminoxyl relative to the macromolecule to which the label is bound. Slow isotropic motion of the carrier may be described by Brownian diffusion, while the nature of the fast stochastic process of the spin label is unknown and the only way to describe it is by substituting and comparing it with well defined model processes. The general applicability of this approach is exemplified by EPR spectra simulations for various types of spin-labelled macromolecules in solutions or in bulk.