arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1012.3119cond-mat.stat-mechcond-mat.softq-bio.BM
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单酶和分子马达的随机热力学

Stochastic thermodynamics of single enzymes and molecular motors

Udo Seifert

摘要:

对于一个单一的酶或分子马达在非平衡溶质浓度的水溶液中运行,热力学描述的发展水平上的一个单独的轨迹状态之间的转换。状态的内能、内禀熵和自由能的概念来自于使用时间尺度分离的一个假设的微观描述。然后,第一定律能量平衡允许唯一地识别在一个转变中耗散的热。在系综水平上与第二定律的一致性,既要求随机熵作为一个跃迁中熵变化的第三个贡献,又要求任何跃迁的前向和后向速率之比的局部细致平衡条件。这些结果遵循没有假设弱耦合之间的酶和溶质,理想的溶液行为或质量作用定律动力学。本方法突出了每个状态的固有熵的关键作用和化学稳定器的物理可疑的作用,推导出第一定律的分子马达受到外力在现实条件下。

英文摘要:

For a single enzyme or molecular motor operating in an aqueous solution of non-equilibrated solute concentrations, a thermodynamic description is developed on the level of an individual trajectory of transitions between states. The concept of internal energy, intrinsic entropy and free energy for states follows from a microscopic description using one assumption on time-scale separation. A first law energy balance then allows the unique identification of the heat dissipated in one transition. Consistency with the second law on the ensemble level enforces both stochastic entropy as third contribution to the entropy change involved in one transition and the local detailed balance condition for the ratio between forward and backward rates for any transition. These results follow without assuming weak coupling between the enzyme and the solutes, ideal solution behavior or mass action law kinetics. The present approach highlights both the crucial role of the intrinsic entropy of each state and the physically questionable role of chemiostats for deriving the first law for molecular motors subject to an external force under realistic conditions.

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