Kinetics of molecular transitions with dynamic disorder in single-molecule pulling experiments.
Kinetics of molecular transitions with dynamic disorder in single-molecule pulling experiments.
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DOI：
10.1063/1.4801331
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发表时间：
2013-05
期刊：
影响因子：
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通讯作者：
Yue Zheng;Ping Li;N. Zhao;Z. Hou
中科院分区：
文献类型：
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作者：
Yue Zheng;Ping Li;N. Zhao;Z. Hou
大分子相变受控于速率常数的大幅波动，称为动态无序。单个或本征跃迁速率和活化自由能可以从单分子拉动实验中提取出来。在这里，我们提出了一个基于广义朗之万方程的理论框架，该方程带有分数高斯噪声和幂函数记忆核，用于研究大分子跃迁的动力学，以解决外力作用下动力学无序对跨越势垒动力学的影响。利用Kramers速率理论，我们计算了分子跃迁的涨落速率常数，以及与力相关的平均寿命、破裂力分布和与速度相关的平均破裂力等实验可及量。特别注意有和没有动力学无序的动力学之间的差异。我们证明，这些差异表现出对外力或拉动速度以及平均力势的势垒高度的强烈和非平凡的依赖性。我们的结果表明，动力学无序是在准确解释单分子拉动实验时应适当考虑的一个重要因素。
Macromolecular transitions are subject to large fluctuations of rate constant, termed as dynamic disorder. The individual or intrinsic transition rates and activation free energies can be extracted from single-molecule pulling experiments. Here we present a theoretical framework based on a generalized Langevin equation with fractional Gaussian noise and power-law memory kernel to study the kinetics of macromolecular transitions to address the effects of dynamic disorder on barrier-crossing kinetics under external pulling force. By using the Kramers' rate theory, we have calculated the fluctuating rate constant of molecular transition, as well as the experimentally accessible quantities such as the force-dependent mean lifetime, the rupture force distribution, and the speed-dependent mean rupture force. Particular attention is paid to the discrepancies between the kinetics with and without dynamic disorder. We demonstrate that these discrepancies show strong and nontrivial dependence on the external force or the pulling speed, as well as the barrier height of the potential of mean force. Our results suggest that dynamic disorder is an important factor that should be taken into account properly in accurate interpretations of single-molecule pulling experiments.