Nishizaka T, Miyata H, Yoshikawa H, Ishiwata S, Kinosita K
Department of Physics, School of Science and Engineering, Waseda University, Tokyo, Japan.
Nature. 1995 Sep 21;377(6546):251-4. doi: 10.1038/377251a0.
The unbinding and rebinding of motor proteins and their substrate filaments are the main components of sliding movement. We have measured the unbinding force between an actin filament and a single motor molecule of muscle, myosin, in the absence of ATP, by pulling the filament with optical tweezers. The unbinding force could be measured repeatedly on the same molecule, and was independent of the number of measurements and the direction of the imposed loads within a range of +/- 90 degrees. The average unbinding force was 9.2 +/- 4.4 pN, only a few times larger than the sliding force but an order of magnitude smaller than other intermolecular forces. From its kinetics we suggest that unbinding occurs sequentially at the molecular interface, which is an inherent property of motor molecules.
运动蛋白与其底物细丝的解离和重新结合是滑动运动的主要组成部分。我们通过用光学镊子拉动细丝，在没有三磷酸腺苷（ATP）的情况下测量了肌动蛋白细丝与肌肉中的单个运动分子肌球蛋白之间的解离力。解离力可以在同一个分子上反复测量，并且在+/- 90度范围内与测量次数和施加负载的方向无关。平均解离力为9.2 +/- 4.4皮牛，仅比滑动力大几倍，但比其他分子间力小一个数量级。从其动力学特性我们推测，解离是在分子界面上依次发生的，这是运动分子的固有特性。
