Which enzyme hydrolyzes ATP to provide energy for muscle contraction?

Which enzyme hydrolyzes ATP to provide energy for muscle contraction? Myosin ATPase does.

Myosin ATPase is the ATP-hydrolyzing activity in the myosin motor protein. It catalyzes ATP + water to produce ADP and inorganic phosphate. The released chemical energy changes the conformation of the myosin head, allowing it to bind actin, produce a power stroke, and then detach when a new ATP molecule binds.

This process is part of the cross-bridge cycle. Calcium does not supply the energy directly; it binds troponin, shifts tropomyosin, and exposes binding sites on actin. ATP is then used by myosin to drive repeated interactions. When ATP is absent, myosin cannot detach normally from actin, which helps explain the stiffness known as rigor mortis after death.

Other enzymes in the answer choices have different jobs. Creatine kinase helps rapidly regenerate ATP from phosphocreatine, phosphofructokinase regulates a step in glycolysis, and acetylcholinesterase breaks down acetylcholine at the neuromuscular junction. They support or regulate muscle function, but they are not the contractile ATPase itself.