轴丝动力蛋白复合体工作循环的化学动力学模型

A Chemical Kinetics Model of Working Cycle for an Axonemal Dynein

ADP的浓度对鞭毛拍击的频率和弯曲的程度有着显著的影响,这一机制尚不明确。本文以轴丝动力蛋白分子水解ATP特性为基础,建立了一个轴丝动力蛋白复合体工作循环的化学动力学模型,该模型既考虑了动力蛋白双头之间的相互协作对化学反应速率的影响,也考虑了ADP与ATP在动力蛋白机械化学循环过程中的竞争关系。模型的数值计算显示,动力蛋白处于各种状态的几率随时间振动,振动的频率及ADP的浓度对鞭毛振动频率的影响,与实验中鞭毛拍击的频率基本相同。上述研究结果表明,轴丝动力蛋白双头协作引起的化学振荡可能是鞭毛拍击的动力学基础。

The concentration of ADP has a significant effect on the frequency of flagellar beating and the degree of bending,but the mechanism is not clear.In this paper,based on the ATP-hydrolysis properties of an axoneme dynein,a chemical kinetic model for the axoneme dynein complex is established,in which both the cooperative interaction between two heads of dynein complex and the competitive relationship between ADP and ATP in the mechanochemical cycle are considered.The numerical calculation of the model shows that the proportion of dynein complex in different states periodically changes with time,and the frequency of variation is closely dependent on the concentration of ADP.These results basically are consistent with the experimental data,to imply that the chemical oscillation induced by the cooperative interaction between two heads of dynein complex maybe the dynamical foundation of flagellar beating.