When the F1 portion of the ATP synthase complex is removed

fromthe

mitochondrial membrane and studied in solution, it hydrolyzes ATPto

ADP. Why

does it not function as an ATP synthase?

ATP synthesis requires energy provided by the electrochemical proton gradient which is used by the F0 subunit of the ATP synthase for rotation of the central stalk. The rotation causes conformational changes in the F1 subunit leading to ATP synthesis.

The F1 subunit has 3 ATP binding sites (β-subunits) differing in ATP binding affinities, they have been reported to work together in hydrolyzing ATP.