Hydrogen peroxide generation by higher plant mitochondria oxidizing complex I or complex II substrates

FEBS Letters

Petrussa, Elisa¹  Braidot, Enrico¹  Macrı̀, Francesco¹  Vianello, Angelo¹ 

[1] Department of Biology and Agro-industrial Economics, Section of Plant Biology, University of Udine, via Cotonificio 108, I-33100 Udine, Italy

关键词: Alternative oxidase;    Antioxygen defence;    Hydrogen peroxide;    Plant mitochondrion;    Reactive oxygen species;    Uncoupling;    ANT;    adenine nucleotide translocator;    CAtr;    carboxyatractylate;    ΔH+;    electrochemical proton gradient;    ΔΨ;    electrical potential difference;    OLIGO;    oligomycin;    PHPA;    p-hydroxyphenylacetate;    Pi;    inorganic phosphate;    PUMP;    plant uncoupling mitochondrial protein;    PVPP;    polyvinylpolypyrrolidone;    ROS;    reactive oxygen species;    TPP+;    thiamine pyrophosphate;    UQH;    ubisemiquinone;   

DOI  :  10.1016/S0014-5793(99)00616-X

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The generation of H₂O₂ by isolated pea stem mitochondria, oxidizing either malate plus glutamate or succinate, was examined. The level of H₂O₂ was almost one order of magnitude higher when mitochondria were energized by succinate. The succinate-dependent H₂O₂ formation was abolished by malonate, but unaffected by rotenone. The lack of effect of the latter suggests that pea mitochondria were working with a proton motive force below the threshold value required for reverse electron transfer. The activation by pyruvate of the alternative oxidase was reflected in an inhibition of H₂O₂ formation. This effect was stronger when pea mitochondria oxidized malate plus glutamate. Succinate-dependent H₂O₂ formation was ca. four times lower in Arum sp. mitochondria (known to have a high alternative oxidase) than in pea mitochondria. An uncoupler (FCCP) completely prevented succinate-dependent H₂O₂ generation, while it only partially (40–50%) inhibited that linked to malate plus glutamate. ADP plus inorganic phosphate (transition from state 4 to state 3) also inhibited the succinate-dependent H₂O₂ formation. Conversely, that dependent on malate plus glutamate oxidation was unaffected by low and stimulated by high concentrations of ADP. These results show that the main bulk of H₂O₂ is formed during substrate oxidation at the level of complex II and that this generation may be prevented by either dissipation of the electrochemical proton gradient (uncoupling and transition state 4-state 3), or preventing its formation (alternative oxidase). Conversely, H₂O₂ production, dependent on oxidation of complex I substrate, is mainly lowered by the activation of the alternative oxidase.

【 授权许可】

Unknown