Chemical modification of the mitochondrial bc1 complex by N,N'-dicyclohexylcarbodiimide inhibits proton translocation.
We report here that N,N'-dicyclohexylcarbodiimide (DCCD) decreases the H/2e stoichiometry of the cytochrome bc1 complex from 3.8 +/- 0.2 (10) to 2.1 +/- 0.1 (8) but has only a minimal effect on the H/2e ratio of cytochrome oxidase under the relatively mild conditions used. The effect on the bc1 complex cannot be explained by uncoupling, by inhibition of electron transport or by selective mitochondrial damage. We conclude that DCCD is an inhibitor of proton translocation within the bc1 complex. There are three possible explanations of this effect: (a) DCCD could alter the pathway of electron flow, (b) DCCD could prevent one of the proton translocation reactions but not electron transport, (c) DCCD could prevent the conduction of the translocated proton to the external phase.
D000818:Animals; D002234:Carbodiimides / Q000494:pharmacology*; D004024:Dicyclohexylcarbodiimide / Q000494:pharmacology*; D004579:Electron Transport / Q000187:drug effects; D014450:Electron Transport Complex III; D066298:In Vitro Techniques; D007425:Intracellular Membranes / Q000187:drug effects; D008930:Mitochondria, Liver / Q000201:enzymology*; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors*; D009247:NADH, NADPH Oxidoreductases / Q000037:antagonists & inhibitors*; D011522:Protons; D011808:Quinone Reductases / Q000037:antagonists & inhibitors*; D051381:Rats; D014475:Uncoupling Agents
D002234:Carbodiimides; D009097:Multienzyme Complexes; D011522:Protons; D014475:Uncoupling Agents; D004024:Dicyclohexylcarbodiimide; D009247:NADH, NADPH Oxidoreductases; D011808:Quinone Reductases; D014450:Electron Transport Complex III