Restoration of high-potential cytochrome b-564 by integration of baker's yeast complex III into liposomes

Cytochrome b-564 in isolated complex III from baker's yeast mitochondria exhibits the midpoint redox potential proper to the low-potential couple (+60 mV, pH 7.2). Incorporation of the complex into liposomes promotes total conversion to the high-potential couple (+170 mV, pH 7.2). The reconstituted system shows electrogenic proton translocation, which is inhibited by the uncoupler CCCP. Deenergizing treatments result, moreover, in reversal of the redox potential change. These results support our previous proposal that cytochrome b-564 acts as a transducer of redox energy into acid-base energy in the complex III region of the respiratory chain.