Involvement of cytochrome bc1 complex and cytochrome c2 in the electron-transfer pathway for NO reduction in a photodenitrifier, Rhodobacter sphaeroides f.s. denitrificans

AbstractThe electron-transfer pathway for NO reduction in a photodenitrifier, Rhodobacter sphaeroides f.s. denitrificans, was studied. A sample of membrane proteins containing cytochrome bc1 complex and NO reductase activity was prepared from chromatophores using cholate/deoxycholate as detergents. The NO reductase activity was separated from the cytochrome bc1 complex by ion-exchange chromatography in the presence of dodecyl maltoside. When duroquinol was used as an electron donor, NO was reduced in the bc1-NO reductase preparation supplemented with cytochrome c2. The reduction was inhibited by antimycin and myxothiazol. These results indicate that the cytochrome bc1 complex, cytochrome c2 and membranous NO reductase are involved in the electron-transfer pathway from quinol to NO in this photodenitrifier