Theoretical Study On The Power Stroke Of Myosin Ⅱ

Power stroke is the core concept in the mechanochemical actin-activated myosin ATPase cycle. It was thought the process of transforming chemical energy into mechanical energy. The size of power stroke should be a constant in conventional concepts, but it measured in different experiments have nothing in common with other.To counter this problem, a new concept of power stroke is proposed in this paper. The experimental data of myosin are explained using this new concept.The text is divided into three chapters. In chapter one, the structure of myosin and the mechanochemical actin-activated myosin ATPase cycle are introduced. Some explain and comparison have been done on the existed working models of myosin. In chapter two, some experimental data of dynamical measurement on single myosin are introduced. The contradictories between experimental data and the theory are pointed out. Chapter three is the main part of this paper. A new concept of myosin power stroke is proposed. Based on the new concepts of myosin power stroke, a four-state model of actin-activated myosin ATPase cycle has been set up. Using the chemical kinetic method, the sizes of power stroke was calculated. The theoretical results shows that the sizes of power stroke depends not only on the equilibrium constant of the power stroke but also on the stiffness of the lever arm and the stiffness of optical trap.Theoretical results is consistent with experimental results.