The Research Of Processive Dynamics Of The Myosin V's Stationary State Motion And Transition Dynamics With Unequel Substeps

Myosin V exist in nerve cells or in pigment cells extensively.Myosin V is a motor involved in different forms of intracellular transport .When the transport can't work,the hair will turn white or the nerve system will break down. Myosin V is one of the myosin superfamily.It is an unconventional motor. The distinct characteristic of Myosin V with the other myosins which do cooperative movement. The mechanism of the myosin V is similar to the kinesin. As a processive motor, a myosin V molecule carries its intracellular cargo for long distances along an actin track, taking multiple steps before detaching and deriving the energy for each step from the hydrolysis of ATP. Myosin V is one of the most important studying object of myosin superfamily. Because it was the first discovered processive motor from the myosin superfamily and due to its unique features, including a very long step size, it has drawn a lot of attention in recent years and now belongs to the best studied motor proteins. The experiments have characterized it mechanically biochemically optically and structurally. These studies have shown that myosin V walks along actin filaments in a hand-over-hand fashion with an average step size of about 36 nm, roughly corresponding to the periodicity of actin filaments. The energy of the hydrolysis of ATP made the myosin V transport the"cargo".These years ,many transition models were constructed,such as elatic lever arm model,2-state transition model and 3-state transition model.But from the viewpoint of the biochemistry,myosin V molecule experience many middle state. At present,it is reasonable to consider that there are 5 middle state in one mechanical and chemical cycle.Therefore,we discuss 5-state model of the myosin V's processive directional movement under the load force.We obtain the velocity as a function of the ATP concentration.The theoretical curves accord with the experimental data.And it explains kinds of the dynamics of the motor under the load force. In addition,We worki out the dwell time as a function of the ATP concentration and the load force by the theory of one dimension N-state transition model.They accord with the experimental data.This work helps us to understand the kinetics mechanism of myosin V better. In addendum B,we have discussed the energetics of molecule motor.