Nuclear magnetic resonance studies of cytochromes c in solution.

Cytochromes c are small soluble proteins, which have been extensively studied by nuclear magnetic resonance spectroscopy. The specific NMR features of paramagnetic proteins are discussed for the oxidized form (paramagnetic shift and line broadening). Early NMR studies have focused on the electronic structure of the heme and its direct environment. The conformations of cytochromes c are now investigated by two-dimensional 1H NMR spectroscopy combined with restrained molecular dynamics. 15N and 13C NMR, which greatly benefit from isotopic enrichment, may help in obtaining reliable 1H assignments and thus high quality solution structure. Finally, hydrogen exchange rates provide insight in the rigidity (and stability) of cytochromes c in both redox states at the atomic level.