Section on Molecular Transport, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, United States of America. Mathematical and Statistical Computing Laboratory, Division for Computational Bioscience, Center for Information Technology, National Institutes of Health, Bethesda, MD 20892, United States of America.
J Phys Condens Matter. 2018 Jun 27;30(25):254006. doi: 10.1088/1361-648X/aac4df. Epub 2018 May 18.
This paper deals with the effect of stochastic gating on the flux of solute molecules through a membrane channel. According to the conventional approach, this flux is given by the product of the flux through the open channel and the probability of finding the channel in the open state. Recently we derived an expression for the flux through a stochastically gated channel (Berezhkovskii and Bezrukov 2017 J. Chem. Phys. 147 084109) that showed that the conventional approach may underestimate the flux at fast gating by orders of magnitude. The present work proposes a novel approach to the problem: while our initial derivation of the expression for the flux focuses on the molecule propagator in the channel, here we treat the problem by considering the steady-state flux through an ensemble of identical stochastically gated channels. We show now that the effect of gating on the flux is independent of the gate position, i.e. whether the gate is located at the channel entrance or exit.
本文研究了随机门控对溶质分子通过膜通道的通量的影响。根据传统方法，该通量由通过开放通道的通量与通道处于开放状态的概率的乘积给出。最近，我们推导出了一个随机门控通道的通量表达式（Berezhkovskii 和 Bezrukov，2017，J. Chem. Phys. 147，084109），该表达式表明，在快速门控时，传统方法可能会将通量低估几个数量级。本工作提出了一种解决该问题的新方法：虽然我们最初的通量表达式推导侧重于通道中的分子传播子，但在这里我们通过考虑相同随机门控通道的稳态通量来处理该问题。我们现在证明，门控对通量的影响与门的位置无关，即门位于通道入口还是出口。
