Gilbert S P, Webb M R, Brune M, Johnson K A
Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park 16802.
Nature. 1995 Feb 23;373(6516):671-6. doi: 10.1038/373671a0.
Direct measurement of the kinetics of kinesin dissociation from microtubules, the release of phosphate and ADP from kinesin, and rebinding of kinesin to the microtubule have defined the mechanism for the kinesin ATPase cycle. The processivity of ATP hydrolysis is ten molecules per site at low salt concentration but is reduced to one ATP per site at higher salt concentration. Kinesin dissociates from the microtubule after ATP hydrolysis. This step is rate-limiting. The subsequent rebinding of kinesin-ADP to the microtubule is fast, so kinesin spends only a small fraction of its duty cycle in the dissociated state. These results provide an explanation for the motility differences between skeletal myosin and kinesin.
对驱动蛋白从微管上解离的动力学、驱动蛋白中磷酸和二磷酸腺苷的释放以及驱动蛋白与微管的重新结合进行直接测量，确定了驱动蛋白三磷酸腺苷酶循环的机制。在低盐浓度下，三磷酸腺苷水解的持续性为每个位点十个分子，但在高盐浓度下会降至每个位点一个三磷酸腺苷。三磷酸腺苷水解后，驱动蛋白从微管上解离。这一步是限速步骤。随后，驱动蛋白 - 二磷酸腺苷与微管的重新结合很快，因此驱动蛋白在解离状态下仅花费其工作周期的一小部分时间。这些结果为骨骼肌肌球蛋白和驱动蛋白之间的运动差异提供了解释。
