Proton NMR study of the cytochrome c:flavodoxin electron transfer complex.

The effects of complex formation with flavodoxin on the proton NMR spectrum of cytochrome c are to change the resonance frequencies and to increase the bandwidths of most of the low and high field heme, Met-80, and His-18 protons. These effects are, in general, more pronounced than has been reported for other cytochrome c complexes. The degree of line broadening for many heme related resonances suggests that complex formation induces changes in the cytochrome structure. These results provide the first spectroscopic evidence which corroborates the proposed model for the cytochrome c: flavodoxin complex (1-3).