The effect of reactive oxygen species generated from the mitochondrial electron transport chain on the cytochrome coxidase activity and on the cardiolipin content in bovine heart submitochondrial particles

The effect of reactive oxygen species (ROS), produced by the mitochondrial respiratory chain, on the activity of cytochrome coxidase and on the cardiolipin content in bovine heart submitochondrial particles (SMP) was studied. ROS were produced by treatment of succinate‐respiring SMP with antimycin A. This treatment resulted in a large production of superoxide anion, measured by epinephrine method, which was blocked by superoxide dismutase (SOD). Exposure of SMP to mitochondrial mediated ROS generation, led to a marked loss of cytochrome coxidase activity and to a parallel loss of cardiolipin content. Both these effects were completely abolished by SOD+catalase. Added cardiolipin was able to almost completely restore the ROS‐induced loss of cytochrome coxidase activity. No restoration was obtained with peroxidized cardiolipin. These results demonstrate that mitochondrial mediated ROS generation affects the activity of cytochrome coxidase via peroxidation of cardiolipin which is needed for the optimal functioning of this enzyme complex. These results may prove useful in probing molecular mechanism of ROS‐induced peroxidative damage to mitochondria which have been proposed to contribute to aging, ischemia/reperfusion and chronic degenerative diseases.