The effect of specific antibodies on oxygen uptake and H⁺ pumping by cytochrome c oxidase vesicles

Antibodies to solubilized cytochrome c oxidse and to subunit III were incubated with liposomal oxidase. In oxygen uptake experiments, the inhibiting effects on RCI of anti-oxidase (primarily anti- subunits II and IV) and anti-III were by different mechanisms: the former, by inhibiting the uncoupled rate; the latter, by stimulating the coupled rate. In experiments with H⁺ translocation, anti-oxidase was without effect, while anti-III was a potent inhibitor of proton pumping. These results are conclusive evidence for redox-linked proton extrusion from the vesicles by the oxidase (and its subunit III).