Surfaces affect ion pairing
Surfaces affect ion pairing
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DOI：
10.1021/jp055043m
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发表时间：
2005-12-22
影响因子：
3.3
通讯作者：
Jacobson, MP
中科院分区：
文献类型：
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作者：
Chorny, I;Dill, KA;Jacobson, MP
在水中，正离子吸引负离子。如果水中两个离子附近存在疏水表面，则可以调节这种吸引力。使用显式和隐式水的计算机模拟，我们研究了嵌入疏水表面的离子如何与水中另一个附近的离子相互作用。使用具有不同曲率的疏水表面，我们发现正离子和负离子之间的接触相互作用受到相邻表面曲率的强烈影响，从而稳定或不稳定离子对。我们还发现，由于表面的存在，溶剂分离离子对 (SSIP) 比接触离子对更稳定。这可能解释了为什么在蛋白质晶体结构中经常发现桥接水。我们还注意到隐式溶剂模型不考虑 SSIP。最后，我们发现存在电荷不对称性：吸引负离子的嵌入正电荷与吸引正离子的嵌入负电荷不同。隐式溶剂模型也无法预测这种不对称性。这些结果可能有助于改进生物学和化学中溶剂化的计算模型。
In water, positive ions attract negative ions. That attraction can be modulated if a hydrophobic surface is present near the two ions in water. Using computer simulations with explicit and implicit water, we study how an ion embedded on a hydrophobic surface interacts with another nearby ion in water. Using hydrophobic surfaces with different curvatures, we find that the contact interaction between a positive and negative ion is strongly affected by the curvature of an adjacent surface, either stabilizing or destabilizing the ion pair. We also find that the solvent-separated ion pair (SSIP) can be made more stable than the contacting ion pair by the presence of a surface. This may account for why bridging waters are often found in protein crystal structures. We also note that implicit solvent models do not account for SSIPs. Finally, we find that there are charge asymmetries: an embedded positive charge attracting a negative ion is different than an embedded negative charge attracting a positive ion. Such asymmetries are also not predicted by implicit solvent models. These results may be useful for improving computational models of solvation in biology and chemistry.