Carrillo-Tripp Mauricio, San-Román María Luisa, Hernańdez-Cobos Jorge, Saint-Martin Humberto, Ortega-Blake Iván
Chemistry Department, Wabash College, P.O. Box 352, Crawfordsville, IN 47933, USA.
Biophys Chem. 2006 Dec 1;124(3):243-50. doi: 10.1016/j.bpc.2006.04.012. Epub 2006 May 3.
Using a simple model, it is shown that the cost of constraining a hydrated potassium ion inside a narrow pore is smaller than the cost of constraining hydrated sodium or lithium ions in pores of radius around 1.5 A. The opposite is true for pores of radius around 2.5 A. The reason for the selectivity in the first region is that the potassium ion allows for a greater distortion of its hydration shell and can therefore maintain a better coordination, and the reason for the reverse selectivity in the second region is that the smaller ions retain their hydration shells in these pores. This is relevant to the molecular basis of ion selective channels, and since this mechanism does not depend on the molecular details of the pore, it could also operate in all sorts of nanotubes.
通过一个简单的模型表明，在半径约为1.5埃的窄孔中限制水合钾离子的成本低于在相同半径孔中限制水合钠或锂离子的成本。而在半径约为2.5埃的孔中情况则相反。在第一个区域具有选择性的原因是钾离子允许其水合壳发生更大程度的变形，因此能够保持更好的配位；而在第二个区域出现相反选择性的原因是较小的离子在这些孔中保留了它们的水合壳。这与离子选择性通道的分子基础相关，并且由于这种机制不依赖于孔的分子细节，它也可能在各种纳米管中起作用。
