Laboratory of Mathematics for Nonlinear Science, Shanghai Key Laboratory for Contemporary Applied Mathematics, Centre for Computational Systems Biology, School of Mathematical Sciences, Fudan University, Shanghai, China.
PLoS One. 2012;7(3):e32717. doi: 10.1371/journal.pone.0032717. Epub 2012 Mar 23.
In this study, through phenomenological comparison of the velocity-force data of processive motor proteins, including conventional kinesin, cytoplasmic dynein and myosin V, I found that, the ratio between motor velocities of two different ATP concentrations is almost invariant for any substall, superstall or negative external loads. Therefore, the velocity of motors can be well approximated by a Michaelis-Menten like formula V = [ATP]k(F)L([ATP] + K(M)), with L the step size, and k(F) the external load F dependent rate of one mechanochemical cycle of motor motion in saturated ATP solution. The difference of Michaelis-Menten constant K(M) for substall, superstall and negative external load indicates, the configurations at which ATP molecule can bind to motor heads for these three cases might be different, though the expression of k(F) as a function of F might be unchanged for any external load F. Verifications of this Michaelis-Menten like formula has also been done by fitting to the recent experimental data.
在这项研究中，通过对包括传统的驱动蛋白、细胞质动力蛋白和肌球蛋白 V 在内的连续运动马达蛋白的速度-力数据进行现象学比较，我发现，对于任何亚稳、超稳或负外部负载，两种不同 ATP 浓度下的马达速度之比几乎不变。因此，马达的速度可以很好地用米氏方程 V = [ATP]k(F)L([ATP] + K(M))来近似，其中 L 是步长，k(F)是在饱和 ATP 溶液中马达运动的一个机械化学循环中外部负载 F 依赖的速率。米氏常数 K(M)在亚稳、超稳和负外部负载下的差异表明，对于这三种情况，ATP 分子能够结合到马达头部的构象可能不同，尽管 k(F)作为 F 的函数的表达对于任何外部负载 F 可能不变。通过拟合最近的实验数据，也验证了这种米氏方程的形式。
