EPR of site-directed spin-labeled proteins: A powerful tool to study structural flexibility

摘要

Electron Paramagnetic Resonance is a spectroscopic technique which, in combination with site-directed spinlabeling, provides structural and dynamic information about proteins in conditions similar to those of their physiological environment. The information is sequence-resolved, as it is based on probing the local dynamics of a paramagnetic label incorporated as a side chain of a selected amino acid. EPR does not impose a limit on the size of the protein or protein complex, as long as it is amenable to site-directed mutagenesis, and is able to obtain reliable distance distributions between two or more labels (identical or different).. The mean value, width and shape of distance distributions, as well as their dependence upon the state of the protein or interactions with physiological partners, provide insight into order-disorder transitions and the roles of protein flexibility.