| 19540189 |
Moser MD, Matsuzaki S, Humphries KM: Inhibition of succinate-linked respiration and complex II activity by hydrogen peroxide. Arch Biochem Biophys. 2009 Aug 1;488(1):69-75. Epub 2009 Jun 18.
Hydrogen peroxide produced from electron transport chain derived superoxide is a relatively mild oxidant, and as such, the majority of mitochondrial enzyme activities are impervious to physiological concentrations. Previous studies, however, have suggested that complex II (succinate dehydrogenase) is sensitive to H (2) O (2)-mediated inhibition. Nevertheless, the effects of H (2) O (2) on succinate-linked respiration and complex II activity have not been examined in intact mitochondria. Results presented indicate that H (2) O (2) inhibits succinate-linked state 3 mitochondrial respiration in a concentration dependent manner. H (2) O (2) has no effect on complex II activity during state 2 respiration, but inhibits activity during state 3. It was found that conditions which prevent oxaloacetate accumulation during state 3 respiration, such as inclusion of rotenone, glutamate, or ATP, blunted the effect of H (2) O (2) on succinate-linked respiration and complex II activity. It is concluded that H (2) O (2) inhibits succinate-linked respiration indirectly by sustaining and enhancing oxaloacetate-mediated inactivation of complex II. |
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