Applications of EPR and Advanced EPR Techniques to Study of Protein Structure and Interactions
The most striking observation that derives from an extensive literature search of applications of electron paramagnetic resonance (EPR) and related techniques is the great diversity of applications and the corresponding diversity of experimental and theoretical methods required to extract information of interest from samples under investigation. Applications include the study of metalloproteins, naturally occurring, long-lived organic radicals, short-lived biological species, and various spin-labeled biological materials. As an example of the utility of application of conventional and advanced EPR techniques to complex biological problems, the chapter begins with a review of studies aimed at a characterization of the structure, physiology, and senescence (aging) of the human red blood cell (RBC). One of the first proteins to be spin-labeled was the major RBC protein, hemoglobin, which was labeled at various sites for the purpose of investigating the conformations of the alpha and beta chains and the relationship of conformation to cooperative oxygen binding.