Das Rahul Kumar, Kolomeisky Anatoly B
Department of Chemistry, Rice University, Houston, Texas 77005-1892, USA.
J Phys Chem B. 2008 Sep 4;112(35):11112-21. doi: 10.1021/jp800982b. Epub 2008 Aug 8.
Motor proteins are active biological molecules that perform their functions by converting chemical energy into mechanical work. They move unidirectionally along rigid protein filaments or DNA and RNA molecules in discrete steps by hydrolyzing ATP (adenosine triphsophate) or related energy-rich compounds. Recent single-molecule experiments have shown that motor proteins experience significant spatial fluctuations during its motion, leading to broad step-size distributions. The effect of these spatial fluctuations is analyzed explicitly by considering discrete-state stochastic models that allow us to compute exactly all dynamic properties. It is shown that for symmetric spatial fluctuations there is no change in mean velocities for weak external forces, while dispersions and stall forces are strongly affected at all conditions. These results are illustrated by several simple examples. Our method is also applied to analyze the effect of step-size fluctuations on dynamics of myosin V motor proteins. It is argued that spatial fluctuations might be used to control and regulate the dynamics of motor proteins.
马达蛋白是一类活性生物分子，它们通过将化学能转化为机械功来履行其功能。它们通过水解三磷酸腺苷（ATP）或相关的富含能量的化合物，沿着刚性蛋白质细丝或DNA和RNA分子以离散的步长单向移动。最近的单分子实验表明，马达蛋白在运动过程中经历显著的空间波动，导致步长分布很宽。通过考虑离散状态随机模型来明确分析这些空间波动的影响，该模型使我们能够精确计算所有动态特性。结果表明，对于对称空间波动，在弱外力作用下平均速度没有变化，而在所有条件下，离散度和失速力都受到强烈影响。通过几个简单的例子来说明这些结果。我们的方法还应用于分析步长波动对肌球蛋白V马达蛋白动力学的影响。有人认为，空间波动可能被用来控制和调节马达蛋白的动力学。
