Effect of ubiquinone extraction on ubiquinol-1 oxidase activity in beef heart mitochondria

Abstract
Extraction of endogenous ubiquinone with different methods does not influence ubiquinol oxidase activity in lyophilized mitochondria in terms ofK M, although a decrease ofV max is sometimes observed. Experiments with submitochondrial particles from a UQ-deficient mutant ofS. cerevisiae confirm the results with UQ-depleted mitochondria and support the idea that endogenous ubiquinone is not required for the oxidation of exogenous ubiquinols by complex III.