You have isolated intact mitochondria from cardiac tissue. Assume all proteins a

Question

You have isolated intact mitochondria from cardiac tissue. Assume all proteins and cofactors (ADP, Pi NAD+, FAD etc.) necessary for electron transport and oxidative phosphorylation are present in excess. You divide a solution of the mitochondria into two test tubes. To the solution in one tube you add Rotenone* (System 1), to the solution in the other tube you add aurovertin* (System 2). To each tube you then add an oxidizable substrate (e.g. pyruvate; assume the citric acid cycle is operational) and measure O2 uptake by means of an oxygen electrode). "note: rotenone inhibits Complex I and aurovertin inhibits ATP synthase 17. What could you add to System 2 to restore oxygen consumption? (assume aurovertin remains bound to ATP synthase). Explain.

Explanation / Answer

Addition of succinate and ATPase of submitochondrial particles

Aurovertin is a antibiotics which binds to beta subinit in F1 ATPase. It is an uncompetitive inhibitor. Addition of succinate and ATPase to a complex of aurovertin it may serve forward reaction of oxidative phosphorylation (eg ATP synthesis) are much more sensitive to aurovertin inhibition than the reverse reaction such as ATP supported reduction of DPN+ by succinate and ATPase of submitochondrial particle.

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