Final answer:
The enzyme in the myosin head that hydrolyzes ATP is ATPase. By hydrolyzing ATP to ADP and Pi, it induces a conformational change in the myosin head, preparing it for the next cycle of muscle contraction where the power stroke occurs upon release of ADP and Pi.
Step-by-step explanation:
The enzyme located in the myosin head that hydrolyzes ATP is called ATPase. This enzyme's activity is essential for muscle contraction and relaxation. During the muscle contraction cycle, ATP binding to the myosin head causes it to detach from actin, and after detachment, the ATP is hydrolyzed to ADP and inorganic phosphate (Pi) by the ATPase activity inherent in the myosin head. The energy released from ATP hydrolysis induces a conformational change, cocking the myosin head into a high-energy position ready for the next cycle of muscle contraction. When the myosin head binds to actin, and the ADP and Pi are released, the power stroke occurs, propelling the actin filament.