Valence selectivity of the gramicidin channel: A molecular dynamics free energy perturbation study

被引:93
作者
Roux, B [1 ]
机构
[1] UNIV MONTREAL,GRP RECH TRANSPORT MEMBRANAIRE,DEPT PHYS,MONTREAL,PQ H3C 3J7,CANADA
基金
英国医学研究理事会;
关键词
D O I
10.1016/S0006-3495(96)79511-5
中图分类号
Q6 [生物物理学];
学科分类号
071011 ;
摘要
The valence selectivity of the gramicidin channel is examined using computer simulations based on atomic models. The channel interior is modeled using a gramicidin-like periodic poly (L, D)-alanine beta-helix. Free energy perturbation calculations are performed to obtain the relative affinity of K+ and Cl- for the channel. It is observed that the interior of the gramicidin channel provides an energetically favorable interaction site for a cation but not for an anion. Relative to solvation in bulk water, the carbonyl CO oxygens can provide a favorable interaction to stabilize K+, whereas the amide NH hydrogens are much less effective in stabilizing Cl-. The results of the calculations demonstrate that, as a consequence of the structural asymmetry of the backbone charge distribution, a K+ cation can partition spontaneously from bulk water to the interior of the gramicidin channel, whereas a Cl- anion cannot.
引用
收藏
页码:3177 / 3185
页数:9
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