ANATOMY

Detailed explanation-1: -At the end of the power stroke, the myosin is in a low-energy position. After the power stroke, ADP is released, but the cross-bridge formed is still in place. ATP then binds to myosin, moving the myosin to its high-energy state, releasing the myosin head from the actin active site.

Detailed explanation-2: -The power stroke pulling myosin along actin filaments during muscle contraction is achieved by a large rotation (≈60°) of the myosin lever arm after ATP hydrolysis. Upon binding the next ATP, myosin dissociates from actin, but its ATPase site is still partially open and catalytically off.

Detailed explanation-3: -According to the concept of Lymn and Taylor (1), the power stroke is driven by the release of the ATP-hydrolysis products ADP and phosphate from the active site.

Detailed explanation-4: -The myosin head moves toward the M line, pulling the actin along with it. As the actin is pulled, the filaments move approximately 10 nm toward the M line. This movement is called the power stroke, as it is the step at which force is produced.

Detailed explanation-5: -This energy is expended as the myosin head moves through the power stroke; at the end of the power stroke, the myosin head is in a low-energy position. After the power stroke, ADP is released; however, the cross-bridge formed is still in place, and actin and myosin are bound together.