Molecular Complexes between Cytochrome <i>b</i>₂ [Yeast L(+)Lactate: Cytochrome <i>c</i> Oxidoreductase] and Cytochrome <i>c</i> in the Crystalline State and in Solution

Abstract

In the crystalline state and in solution, cytochrome b 2 (yeast l ‐lactate: cytochrome c oxidoreductase) is shown to form a very stable complex with cytochrome c (from horse heart or yeast). This complex is characterized by a cytochrome c /cytochrome b 2 heme ratio of about 0.25 which corresponds to the binding of one cytochrome c molecule to one tetraheme enzyme unit. Its formation is pH sensitive and prevented by salts but not by antimycin A. The prosthetic flavin group of cytochrome b 2 is not required for the binding of cytochrome c .