Self-organized enhancement of conductivity in biological ion channels

Tindjong, Rodrigue and Kaufman, Igor and Luchinsky, Dmitrii G. and McClintock, Peter V. E. and Khovanov, Igor A. and Eisenberg, R. S. (2013) Self-organized enhancement of conductivity in biological ion channels. New Journal of Physics, 15 (10): 103005. ISSN 1367-2630

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Abstract

We discuss an example of self-organisation in a biological system. It arises from long-range ion-ion interactions, and it leads us to propose a novel mechanism of enhanced conduction in ion channels. The underlying mechanism involves charge fluctuations near the channel mouth, amplified by the mismatch between the relative permittivities of water and the protein of the channel walls. We use Brownian dynamics simulations to show that, as in conventional ``knock-on'' permeation, these interactions can strongly enhance the channel current; but unlike the conventional mechanism the enhancement occurs without the instigating bath ion entering the channel. The transition between these two mechanisms is clearly demonstrated, emphasizing their distinction. A simple model accurately reproduces the observed phenomena. We point out that electrolyte plus protein of low relative permittivity are universal in living systems, so that long-range ion-ion correlations of the kind considered must be common.