Occurrence of c-Type Cytochrome in Mycobacterium lepraemurium

Abstract

The existence of c-type cytochrome in Mycobacterium lepraemurium was examined. The dithionite-treated cell-free extracts exhibited absorption peaks of cytochromes a + a3 and b, whereas the alpha band of c-type cytochrome at 552 nm was obscured by the large absorption peak of cytochrome b at 560 nm. The addition of NADH, NADPH, or succinate to cell-free extracts caused the reduction of b- and c-type cytochromes to nearly the same extent and thus the difference spectra displayed distinct separate peaks of b- and c-type cytochromes at 562 and 552 nm, respectively. The cell-free extracts treated with ascorbate showed absorption bands of cytochrome types c and a + a3, whereas the addition of succinate to a system preinhibited by antimycin A revealed the absorption bands of cytochrome b only. The absorption spectrum of the pyridine hemochromogens of M. lepraemurium was similar to that of mammalian cytochrome c. The results clearly indicated that, in addition to cytochromes of the a + a3 and b type, c-type cytochrome is also present in M. lepraemurium.