Cytochrome system in Schizophyllum commune

Abstract

The respiratory characteristics of S. commune mycelium grown on solid and liquid media have been examined. The O2 uptake can be markedly inhibited by cyanide, azide, CO (in the dark only), antimycin A, and phenylmercuric acetate, while copper-combining agents have little effect. At low concentrations, DNP stimulates the respiration and inhibits growth, but at higher concentrations both processes are inhibited. Particles (mitochondria) isolated by differential centrifugation from homogenates of the mycelium showed the following activities: cytochrome c oxidase; DPNH-, TPNH-, and succinic-cytochrome c reductases; DPNH oxidase; succinoxidase. Spectrophotometric observations of the particle components which are reduced by DPNH revealed the presence of roughly equi-molar concentrations of a-, b-, and c-type cytochromes and a molar excess of flavoprotein. It is concluded that respiration in S. commune mycelium involves the transfer of electrons from substrates to molecular O2 through a chain which includes these components.