Ion hydration in nanopores and the molecular basis of selectivity.

Authors:
Dr. Mauricio Carrillo-Tripp, PhD
Dr. Mauricio Carrillo-Tripp, PhD
Biomolecular Diversity Laboratory, Cinvestav
Associate Profesor
Computational Biophysics
Irapuato, Guanajuato | México

Biophys Chem 2006 Dec 3;124(3):243-50. Epub 2006 May 3.

Chemistry Department, Wabash College, P.O. Box 352, Crawfordsville, IN 47933, USA.

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.

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http://dx.doi.org/10.1016/j.bpc.2006.04.012DOI Listing
December 2006
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