Kitamura Kazuo, Yanagida Toshio
Single Molecule Processes Project, ICORP, JST, 2-4-14 Senba-higashi, Mino, Osaka 562-0035, Japan.
Biosystems. 2003 Sep;71(1-2):101-10. doi: 10.1016/s0303-2647(03)00114-x.
The epoch-making techniques for manipulating a single myosin molecule have recently been developed, and the unitary mechanical reactions of a single actomyosin, muscle motor molecule, are directly measured. The data show that the unitary mechanical step during sliding along an actin filament of approximately 5.5 nm, but groups of two to five rapid steps in succession produce displacements of approximately 11-30 nm. The instances of multiple stepping are produced by single myosin heads during one biochemical cycle of ATP hydrolysis. Thus, the coupling between ATP hydrolysis cycle and mechanical step is variable, i.e. loose-coupling. Such a unique operation of actomyosin molecules is different from that of man-made machines, and most likely explains the flexible and effective mechanisms of molecular machines in the biosystems.
最近开发出了划时代的用于操纵单个肌球蛋白分子的技术，并且能够直接测量单个肌动球蛋白（肌肉运动分子）的单一机械反应。数据表明，沿着肌动蛋白丝滑动时的单一机械步长约为5.5纳米，但连续的两到五步快速步长会产生约11 - 30纳米的位移。多个步长的情况是由单个肌球蛋白头部在ATP水解的一个生化循环中产生的。因此，ATP水解循环与机械步长之间的耦合是可变的，即松耦合。肌动球蛋白分子的这种独特运作不同于人造机器，很可能解释了生物系统中分子机器灵活且有效的机制。
