Membrane-associated cytochrome cy of Rhodobacter capsulatus is an electron carrier from the cytochrome bc1 complex to the cytochrome c oxidase during respiration

Isolation of a group of Rhodobacter capsulatus mutants, in which the water-soluble cytochrome c2 (cyt c2) or the membrane-bound c-type cytochrome (cyt cy) is absent, helps study the involvement of cyt cy in respiratory electron transport, with or without the alternate respiratory pathway that is dependent on quinol oxidase. Assessment of the mutants' growth and inhibitor responsiveness distribution, their rates of respiration in a particular inhibitor environment and c-type cytochrome oxidation-reduction kinetics reveals that the bc1 complex and cyt c oxidase are linked by cyt cy during respiratory electron transfer.