ABSTRACT
The method of spin label and probe is most widely used in molecular biology for solving various structural and dynamic problems. Physical-chemical properties of spin labels, attached to certain functional groups in biological systems, depend on the presence of corresponding compounds affecting the properties. 3-cm Electron Paramagnetic Resonance (EPR) spectra of radicals were found to be quite sensitive to temperature and water content in the interior of micelles. However, it was found impossible in the framework of traditional EPR spectroscopy to characterize quantitatively the microenvironment properties of radicals and to identify the nature of their motion in micelle shells and near the active center of an enzyme. Since EPR spectra of nitroxide radicals are well resolved at the 2-mm wave band and are more sensitive to the parameters of a model and motion anisotropy, they can be used for the determination of correlation time.
