四态肌球蛋白Ⅴ持续运动特性研究

Study on the Processivity of Four-state Myosin Ⅴ

定量分析肌球蛋白Ⅴ与ATP的结合速率以及能反映肌球蛋白Ⅴ持续运动的相关参数,对于深入探索肌球蛋白Ⅴ持续运动的内在机制具有重要意义.本文对肌球蛋白Ⅴ结合ATP过程中结合速率满足的规律进行推导,发现其满足米曼方程的形式.针对肌球蛋白Ⅴ建立四态机械化学耦合模型,利用动力学方程,推导出驻留时间和运动速度的解析解,并分析了在不同ATP、ADP以及负载条件下,驻留时间和运动速度的变化规律.结果表明,ATP和ADP之间的竞争是决定驻留时间分布的关键因素;驻留时间与向后负载的施加成正相关;随ADP浓度的增加,运动速度减小,运动速度达到饱和值时所需的ATP浓度增大;对比向前负载和向后负载发现向后负载更能影响运动速度.所得结果与实验值基本一致.

Quantitative analysis of the binding rate of myosin Ⅴ with ATP and related parameters that can reflect the processivity of myosin Ⅴ were greatly significant to explore the intrinsic mechanism of the processivity of myosin Ⅴ.The law was deduced,which refers to the binding rate of myosin Ⅴ with ATP and it was found to satisfy the form of the Michaelis-Menten equation.A four-state mechanochemical coupling model was established for myosin Ⅴ,and the analytical solutions of the dwell time and the velocity of movement were derived by using the dynamic equation.The variations of the dwell time and the velocity of movement were analyzed under different ATP,ADP and load conditions.The results were as follows four conclusions:the competition between ATP and ADP was a key factor in determining the dwell time distribution;the dwell time was positively correlated with the backward load;as the ADP concentration increases,the velocity decreases,and the required ATP concentration increases when the velocity reaches saturation;comparing the forward load and the backward load,it was found that the backward load was more likely to affect the velocity of movement.The results were basically consistent with the experimental values.