On the site of action of the inhibition of the mitochondrial respiratory chain by lipoxygenase.

Treatment of beef-heart submitochondrial particles with reticulocyte lipoxygenases gives rise to a strong irreversible inhibition of the NADH and succinate oxidase activities. This is not accompanied by any loss of the Fe-S clusters of the respiratory chain as determined by EPR spectroscopy. The inhibitory blockage is located between both the NADH and succinate dehydrogenases and Q-10. The inhibitory action of treatment with lipoxygenase also takes place in the absence of Q-10. The Fe-S clusters of the mitochondrial outer membrane are destroyed by lipoxygenase treatment, without any effect on the rotenone-insensitive NADH: cytochrome c oxidoreductase activity. It is concluded that these clusters are not involved in this enzyme.