Structural characterization of isolated mitochondrial cytochrome c₁

Resonance Raman spectroscopy (RRS) has been employed to characterize cytochromes c₁ isolated from bc₁ complexes of beef heart mitochondria and Rhodopseudomonas sphaeroides. The data obtained in this study extend the physical characterization of cytochromes c₁ and focus on the effects of the local protein environment on the heme active site. While the general characteristics of the cytochromes c₁ are similar to those of smaller soluble cytochromes c, the behavior of several core-size and ligation-sensitive heme modes reveal that significant systematic differences exist between those species. These, most likely, result from changes in the heme axial-lignad interactions.