Partial sequences of high-molecular-weight cytochrome c isolated from Desulfovibrio vulgaris Miyazaki.

A polyhemic high-molecular-weight cytochrome c (hmc) of Mr 67,000 was purified from Desulfovibrio vulgaris Miyazaki. This cytochrome is composed of a single peptide chain. Unlike other c-type cytochromes, hmc deteriorates slowly in atmospheric oxygen. Two peptide fragments of Mr 33,100 (L peptide) and Mr 19,100 (S peptide) were isolated and their N-terminal sequences determined to be PLPGATGEQRADLVEIGVMAKFTNLELPKV (L peptide) and GTLPAVAIPEFVTIGVLK (S peptide). The established sequence of the L peptide is homologous to the N-terminal sequence of cytochrome c3 (Mr 26,000) from D. vulgaris Hildenborough, in spite of discrepancies observed in the molecular size and subunit structure of these cytochromes.