Cytochromec′

Abstract

Cytochromes c′ are heme proteins presumably involved in electron transport and the name cytochrome c′ is used to distinguish these high‐spin heme proteins from the low‐spin mitochondrial cytochromes c . The heme group is covalently bound by thioether bonds between the two vinyl groups of the heme and the two cysteinyl side chains in a sequence, ‐Cys‐X‐Y‐Cys‐His‐, typical of cytochromes c . The histine occupies the fifth axial coordination position. Most cytochromes c′ are isolated as homodimers of ca 2 × 14 kDa and each monomer consists of an anti‐parallel four‐α‐helical bundle, which defines the heme‐binding pocket.