Spin Labeling Methods

Abstract

This chapter is a brief review of the main results obtained by the methods of spin and triplet (phosphorescence) labels. Methods of physical labelling using unpaired electron spins such as nitroxide and other stable radicals, transition and lanthanide metal complexes, and phosphoresce chromophores in the triplet state have proven to be powerful tool for the study of structure and dynamics of a body of complex molecular objects, biological system in particular. Structure, molecular breathing, conformational transitions in labeled biological polymers and membranes in solid and liquid states have been investigated using the arsenal of traditional and recently developed physical methods. Interest to spin labeling is fueled by the many promising applications. Measurements of electric potential, redox status, oxygen concentration and acidity in various materials including those of biological relevance are amenable for the physical labeling techniques as well.