The mechanism of antibody inhibition of proton pumping by cytochrome oxidase vesicles.

Antibodies previously shown to inhibit vectorial proton translocation through cytochrome oxidase vesicles were converted to F(ab')2 and Fab'. Neither fragment inhibited proton pumping, although binding capacity was present. However, when a surrogate Fc was added to F(ab')2, inhibition of proton translocation was restored; indicating that the inhibition is due to steric hindrance. These results provide insight into mechanisms of energy transduction by oxidase.