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arXiv 0710.4359cond-mat.softcond-mat.stat-mech
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相互作用对跨膜通道分子通量和波动的影响

Effect of Interactions on Molecular Fluxes and Fluctuations in the Transport Across Membrane Channels

Anatoly B. Kolomeisky, Stanislav Kotsev

摘要:

利用可精确求解的一维离散状态随机模型,从理论上研究了分子跨膜通道的输运。通过一组具有不同能量的结合位点来模拟分子与膜孔之间的相互作用。结果表明,相互作用势强烈影响的粒子电流以及易位分子的数量波动。对于小的浓度梯度的吸引力的网站导致最大的电流和波动,而排斥的相互作用产生最大的通量和分散体的大浓度梯度。导致最大电流和最大波动的相互作用能仅对于局部对称势是相同的,而它们对于局部非对称势是不同的。讨论了具有最大电流和最小色散的最佳易位输运的条件。有人认为,在这种情况下的相互作用强度是独立的平均力的潜力的局部对称性。此外,相互作用势的整体不对称性的影响进行了研究,它表明,它也强烈影响粒子移位动力学。这些现象可以通过分析颗粒进入和离开通道中结合位点的细节来解释。

英文摘要:

Transport of molecules across membrane channels is investigated theoretically using exactly solvable one-dimensional discrete-state stochastic models. An interaction between molecules and membrane pores is modeled via a set of binding sites with different energies. It is shown that the interaction potential strongly influences the particle currents as well as fluctuations in the number of translocated molecules. For small concentration gradients the attractive sites lead to largest currents and fluctuations, while the repulsive interactions yield the largest fluxes and dispersions for large concentration gradients. Interaction energies that lead to maximal currents and maximal fluctuations are the same only for locally symmetric potentials, while they differ for the locally asymmetric potentials. The conditions for the most optimal translocation transport with maximal current and minimal dispersion are discussed. It is argued that in this case the interaction strength is independent of local symmetry of the potential of mean forces. In addition, the effect of the global asymmetry of the interaction potential is investigated, and it is shown that it also strongly affects the particle translocation dynamics. These phenomena can be explained by analyzing the details of the particle entering and leaving the binding sites in the channel.

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