Plasmon waveguide resonance spectroscopic evidence for differential binding of oxidized and reduced rhodobacter capsulatus cytochrome [c.sub.2] to the cytochrome b[c.sub.1] complex mediated by the conformation of the Rieske iron-sulfer protein

The measurement of the dissociation constants for the binding of Rhodobacter capsulatus cytochrome [c.sub.2] and its K93P mutant to the cytochrome b[c.sub.1] complex embedded in a phospholipid bilyaer reveal that the dual conformation of the Rieske protein is primarily responsible for biphasic binding of oxidized cytochrome [c.sub.2] to cytochrome [c.sub.1].