Cytochrome c‐550 mediates electron transfer from inducible periplasmic c‐type cytochromes to the cytoplasmic membrane of Paracoccus denitrificans

Electron transfer from periplasmic cytochromes c to the membrane-bound respiratory chain has been studied with the isolated cytochromes and membrane preparations from Paracoccus denitrificans. When reduced cytochromes were incubated with spheroplasts only the constitutive cytochrome c-550 was rapidly oxidized. The inducible cytochromes c-551i and c-553i were not oxidized at appreciable rates. Cytochrome c-550 was able to mediate the transfer of electrons from either cytochrome c-551i or cytochrome c-553i to the membrane preparation.