Since A. Kowalsky's first report of the spectrum of cytochrome c in 1965, interest in the detection, assignment and interpretation of paramagnetic molecules has surged, especially in the last decade.
Two classes of systems have played a key role in the development of the field: heme proteins and iron-sulfur proteins. These two systems are unique in many respects, one of which is that they contain well-defined chromophores, each of which can be studied in detail outside the protein matrix. They are the most successfully studied macromolecules, and the first eight and last six of...