An atp synthase is an enzyme that catalyzes formation of atp from adp and inorganic phosphate. under what conditions would you expect an atp synthase to catalyze the reverse reaction (hydrolysis of atp)? when there is an excess of atp and low amounts of phosphate when there is an excess of phosphate and low amounts of atp when there is an excess of adp an atp synthase will not catalyze the hydrolysis reaction