Action of DCCD on the H+/O stoichiometry of mitoplast cytochrome c oxidase.
The mechanistic H+/O ejection stoichiometry of the cytochrome c oxidase reaction in rat liver mitoplasts is close to 4 at level flow when the reduced oxidase is pulsed with O2. Dicyclohexylcarbodiimide (DCCD) up to 30 nmol/mg protein fails to influence the rate of electron flow through the mitoplast oxidase, but inhibits H+ ejection. The inhibition of H+ ejection appears to be biphasic; ejection of 2-3 H+ per O is completely inhibited by very low DCCD, whereas inhibition of the remaining H+ ejection requires very much higher concentrations of DCCD. This effect suggests the occurrence of two types of H+ pumps in the native cytochrome oxidase of mitoplasts.
Lehninger
A L
AL
Reynafarje
B
B
Costa
L
L
D000818:Animals; D001692:Biological Transport; D002234:Carbodiimides / Q000494:pharmacology*; D002417:Cattle; D004024:Dicyclohexylcarbodiimide / Q000494:pharmacology*; D004579:Electron Transport; D003576:Electron Transport Complex IV / Q000378:metabolism*; D004734:Energy Metabolism; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism; D007700:Kinetics; D008081:Liposomes / Q000378:metabolism*; D008930:Mitochondria, Liver / Q000187:drug effects / Q000201:enzymology*; D009206:Myocardium / Q000201:enzymology; D010101:Oxygen Consumption; D011522:Protons; D051381:Rats
D002234:Carbodiimides; D007473:Ion Channels; D008081:Liposomes; D011522:Protons; D004024:Dicyclohexylcarbodiimide; D003576:Electron Transport Complex IV