The charge stoichiometry of cytochrome c oxidase in the reconstituted system.
Purified cytochrome c oxidase was reconstituted into phospholipid vesicles having high internal pH buffering capacity. In the presence of valinomycin, 2 K+ ions were taken up by the vesicles per electron transferred from cytochrome c to oxygen. The charge stoichiometry of 2 was obtained from simultaneous measurement of changes of K+, H+, and oxygen in the medium after addition of the reductant ascorbate/TMPD (N,N,N',N'-tetramethyl-p-phenylenediamine). The changes in oxygen concentration were measured with a fast responding oxygen electrode (90% response time, 0.4 s). The existence of a proton pump in cytochrome c oxidase could thus be confirmed, and its charge stoichiometry measured, in a reconstituted system uncomplicated by other respiratory chain components.
D000818:Animals; D002417:Cattle; D003576:Electron Transport Complex IV / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008081:Liposomes; D009206:Myocardium / Q000201:enzymology; D010101:Oxygen Consumption; D010743:Phospholipids; D011188:Potassium / Q000378:metabolism; D014634:Valinomycin / Q000494:pharmacology
D008081:Liposomes; D010743:Phospholipids; D014634:Valinomycin; D003576:Electron Transport Complex IV; D011188:Potassium