Why is gramicidin valence selective? A theoretical study.
Why is gramicidin valence selective? A theoretical study.
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为什么短杆菌肽具有价态选择性？
DOI：
10.1016/s0006-3495(87)83391-x
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发表时间：
1987
影响因子：
3.4
通讯作者：
Jordan,PC
中科院分区：
文献类型：
--
作者：
Sung,SS;Jordan,PC
计算对比了通道溶剂化能的铯离子和氯离子与水在类革兰草毒素通道。阳离子的能量分布在通道入口呈深井状；在单锉区域内，溶剂化能大致恒定。阴离子表现出完全不同的能量分布。通道入口存在能量障壁；如果离子能越过这个屏障，它在通道内就会相当稳定。在通道入口，计算出阴离子和阳离子之间的溶剂化能差约为15 kcal mol-1。这与氯离子既不渗透也不阻塞通道的观察结果完全一致，因为离子进入的估计速率约为0.01-10 (-5)s-1，远低于通道二聚体解离成单体的速率。
Calculations contrasting the channel solvation energy for cesium ions and chloride ions associated with water in gramicidin-like channels are presented. The energy profile for the cation exhibits a deep well at the channel entrance; within the single file region the solvation energy is roughly constant. The anion exhibits a totally different energy profile. There is an energy barrier at the channel entrance; if the ion could surmount this barrier, it would be quite stable within the channel. At the channel entrance, the calculated solvation energy difference between anion and cation is approximately 15 kcal mol-1. This is completely consistent with the observation that chloride neither permeates nor blocks the channel since the estimated rate of ion entry would be approximately 0.01–10(-5) s-1, far slower than the rate at which the channel dimer dissociates into monomers.