| The power of muscle contraction comes from muscle myosin II.During the Myosin II work cycle,the process of converting chemical energy into mechanical energy is called the power stroke.The traditional concept of power stroke believes that power stroke occurs after the strong binding state of myosin and actin filaments is formed,and the dynamic stroke is fixed.However,the dynamic stroke values measured by various myosin single molecule experiments are not the same,and there are contradictions between traditional theory and experiment.To solve this problem,the biophysics group of Inner Mongolia University proposed a new mechanochemical coupling model of myosin II working cycle.It is considered that the power stroke occurs in the process from weak binding state to strong binding state,and the power stroke is not a constant value.As the experiment progressed,the reaction rate constants accumulated for each step of the myosin cycle.On the premise that the experimental data of reaction rate constant can be found,an eight-state model is established to reflect the details of myosin working cycle as much as possible,and the rationality of the model established by biophysics group of Inner Mongolia University is further explained from the perspective of energy transformation.Based on the eight-state model of mechanochemical coupling of myosin II,the chemical dynamics equation of its working cycle was given,and the proportion of each state in the model was calculated by combining with the existing experimental data.From the angle of energy transformation,it is qualitatively proved that it is possible for the dynamic stroke to occur in the process from weakly bound state to strongly bound state,but impossible for it to occur after the formation of strongly bound state.The above work is a new attempt to study the release rate of energy during muscle contraction. |
