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

Abstract

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 redoxlinked proton extrusion from the vesicles by the oxidase (and its subunit III). Cytochrome c oxidase Reconstituted vesicle Proton pumping Chemiosmosis

Characterization of electron-transfer and proton-translocation activities in bovine heart mitochondrial cytochrome c oxidase deficient in subunit III

“…Our results support the findings of Penttila (1983), Thompson et al (1984), andThelen et al (1985) and provide further evidence that electron transfer in cytochrome c oxidase is loosely coupled to vectorial proton translocation. Other experimental evidence that supports this concept is that DCCD blocks proton-translocation activity to a much greater extent than electron-transfer activity and that polyclonal antibodies raised against subunit III block vectorial proton translocation in phospholipid vesicles (Chan & Freedman, 1983). These results taken together suggest that the subunit(s) where protons are mechanistically released by electron transfer and the subunit domain (perhaps subunit III) that translocates the protons across the membrane is (are) different (Casey et al, 1980: Thompson et al, 1984.…”

Effects of subunit V antibodies on the topology of the subunit and the activity of beef heart cytochrome-c oxidase

“…The effect of antisubunit V or antioxidase on COV was determined as described by Chan and Freedman (1983) for antisubunit ILI, with some modifications. Cytochrome-c oxidase was incorporated into the phospholipid vesicles by sonication.…”

Reactive Oxygen Intermediates in Biochemistry

“…Probably all of the redox metal centers are located in the two largest subunits. Subunit three has been implicated in the proton translocating activity [ (45,(57)(58)(59)(60), but see also (61)]. …”