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Updated: Aug 11, 2026

Recapitulation of an Ion Channel IV Curve Using Frequency Components
Published on: February 8, 2011
Incidence of partial charges on ion selectivity in potassium channels
Philippe Huetz1, Céline Boiteux, Mylène Compoint
1Laboratoire de Physique Moléculaire, UMR CNRS 6624, Faculté des Sciences et Techniques, La Bouloie, Université de Franche-Comté, 25030 Besançon cedex, France. philippe.huetz@univ-fcomte.fr
Abstract:
Potassium channels are membrane proteins known to select potassium over sodium ions at a high diffusion rate. We conducted ab initio calculations on a filter model of KcsA of about 300 atoms at the Hartree-Fock level of theory. Partial charges were derived from the quantum mechanically determined electrostatic potential either with Merz-Kollman or Hinsen-Roux schemes. Large polarization and/or charge transfer occur on potassium ions located in the filter, while the charges on sodium ions remain closer to unity. As a result, a weaker binding is obtained for K(+) ions. Using a simplified version of a permeation model based on the concerted-motion mechanism for ion translocation within the single-file ion channel [P. H. Nelson, J. Chem. Phys. 117, 11396 (2002)], we discuss how differences in polarization effects in the adducts with K(+) and Na(+) can play a role as for ionic selectivity and conductance.
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