Extract Motive Energy from Single-Molecule Trajectories
Extract Motive Energy from Single-Molecule Trajectories
复制标题
从单分子轨迹中提取动力能
DOI：
10.1021/acs.jpcb.2c06802
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Zhisong Wang
中科院分区：
文献类型：
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作者：
Ruizheng Hou;Zhisong Wang
来自非平衡展开实验的单分子轨迹被广泛用于恢复生物分子的固有自由能轮廓。来自类似的单分子实验的分子马达的轨迹可能被映射到倾斜的自由能分布上的偏向扩散。这样的有效势不再是静态平衡性质，它如何有助于分子马达的研究尚不清楚。在这里，我们介绍了一种方法，以现实的时空分辨率从运动轨迹推导出有效势，并发现该势产生电机的失速力─，这个量不仅表征电机的发电能力，而且在很大程度上决定其能量效率。有趣的是，这种势允许从以单一阻力甚至零力记录的轨迹中提取发动机的失速力，这与来自两个分子发动机模型的轨迹以及来自真实人造发动机的实验轨迹相验证。这一发现极大地降低了失速力测量的难度，使其甚至可以用于无力的光学跟踪实验(通常被认为与失速力的确定无关)。这项研究进一步提供了一种实验测量亚微观方向性─的第二定律规定的最小能量价格的方法，这是一个以前难以捉摸但在热力学上很重要的量，与分子马达的有效能量转换有关。
Single-molecule trajectories from nonequilibrium unfolding experiments are widely used to recover a biomolecule’s intrinsic free-energy profile. Trajectories of molecular motors from similar single-molecule experiments may be mapped to biased diffusion over an inclined free-energy profile. Such an effective potential is not a static equilibrium property anymore, and how it can benefit molecular motor study is unclear. Here, we introduce a method to deduce this effective potential from motor trajectories with realistic temporal–spatial resolution and find that the potential yields a motor’s stall force─a quantity that not only characterizes a motor’s force-generating capacity but also largely determines its energy efficiency. Interestingly, this potential allows the extraction of a motor’s stall force from trajectories recorded at a single resisting force or even zero force, as verified with trajectories from two molecular motor models and also experimental trajectories from a real artificial motor. This finding drastically reduces the difficulty of stall force measurement, making it accessible even to force-incapable optical tracking experiments (commonly regarded as irrelevant to stall force determination). This study further provides a method for experimentally measuring a second-law-decreed least energy price for submicroscopic directionality─a previously elusive but thermodynamically important quantity pertinent to efficient energy conversion of molecular motors.