The non-coupled substrate oxidation mediated by components of the electron transport chain that are not coupled to energy accumulation (such as plant alternative oxidase and rotenone-insensitive NADH dehydrogenases) and uncoupled respiration are peculiar features of plant mitochondria. The physiological significance of such energy-wasting oxidation processes is still debated. It is proposed that non-coupled oxidation could regulate the level of reduction of components of the electron transport chain and the rate of one-electron reduction of oxygen, thereby affecting the rate of formation of reactive oxygen species.

Abbreviations used: CoQ, coenzyme Q; ROS, reactive oxygen species.

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Author notes

679th Meeting of the Biochemical Society held at the University of Essex, Colchester, 2–4 July 2003