Chemical Modification of the Mitochodrial bc1 by N,N′ ‐Dicyclohexylcarbodiimide Inhibits Proton Translocation

Abstract
We report here that N,N/i′‐dicyclohexylcarbodiimide (DCCD) decreases the H2e stoichiometry of the mytochrome bc1 complex from 308 ± 0.2 (10) to 201 ± 0.1 (8) but has only a minimal effect on the H2e ratio of cytochrome oxidase under the relatively mild condition used. The veffect on the bc1 complex connot 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 ther bc1 complex. There are three possible explanation of this effect: (a) DCCD could alter the pathway of electron flow, (b) DCCD could prevent one of the proton translocation reations but not electrton transport, (c) DCCD could prevent the couduction of the translocated proton to the external phase.

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