Introduction

Since the October of 2005, I have been working with Robert S. Eisenberg, Dirk Gillespie, Wolfgang Nonner, Douglas  Henderson, and Mónika Valiskó (a cooperation started in 2000) on the selectivity mechanism of Calcium and Sodium channels.

Simple reduced models of the selectivity filter have been constructed. The main feature of these models is that amino acid side chains (EEEE in the case of Ca channel and DEKA in the case of Na channel) extend into the ionic pathway forming a crowded flexible ionic environment for the passing ions. Changing basic physical and geometrical parameters of the model (radius of the pore, dielectric constant of the protein, composition of structural groups in the filter -- all are evolutionary driven variables determined by the protein structure) we were able to a wide range of Na⁺ over Ca⁺⁺ and Na⁺ over K⁺ selectivity characteristic of Ca and Na channels.

We used the Monte Carlo simulation method and developed novel and efficient numerical techniques to compute the induced charge that appears on the dielectric boundary between the protein and the electrolyte.