Control of superoxide production in mitochondria from maize mesocotyls

To understand the biochemical events that control the generation of superoxide, the effect of inhibiting the respiratory complexes III and IV (C-III and C-IV) and alternative oxidase (AOX) on the rate of superoxide production was analyzed in mitochondria from maize seedlings. To increase superoxide production, it was required to inhibit C-III or C-IV by at least 30% or 50%, respectively. Below this inhibition threshold, AOX exerted the highest degree of control on superoxide production, whereas above it, the highest degree of control was exerted by G IV. The contribution of C-III to control superoxide production became significant when AOX activity was modulated. (C) 2004 Published by Elsevier B.V. on behalf of the Federation of European Biochemical Societies.