Cytochromes from Mycobacterium phlei: I. Isolation and spectral properties of a mixture of cytochromes ( a + a3) ( o)

Abstract

A complex containing cytochromes a + a 3 and cytochrome o was isolated from Mycobacterium phlei by solubilization with Triton X-100 and subsequent digestion with trypsin. Further purification was achieved by fractionation with ammonium sulfate. The spectra of the oxidized, the reduced, the pyridine hemochromogens, the carbon monoxide, and the cyanide complexes of cytochromes a + a 3 and cytochrome o were presented. The results obtained with cytochromes a + a 3 were similar to those described for mammalian systems. Over a pH range of 6.0 to 8.0 both cytochrome a 3 and o were reducible by ascorbate- N,N,N′,N′-tetramethylphenylenediamine or by NADH plus a catalytic amount of M. phlei electron transport particles. However, cytochrome o was reducible by dithionite only when carbon monoxide or cyanide treatment preceded chemical reduction. The chemical reduction of cytochrome a 3 was found to be independent of the order of addition of carbon monoxide or cyanide.