Effect of Local Binding on Stochastic Transport in Ion Channels

Kaufman, I. Kh and Gibby, W. A. T. and Luchinsky, D. G. and McClintock, P. V. E. (2017) Effect of Local Binding on Stochastic Transport in Ion Channels. arXiv.

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Ionic Coulomb blockade (ICB) is an electrostatic phenomenon recently discovered in low-capacitance ion channels/nanopores. Depending on the fixed charge that is present, ICB strongly and selectively influences the ease with which a given type of ion can permeate the pore. The phenomenon arises from the discreteness of the charge-carriers, the dielectric self-energy, an electrostatic exclusion principle, and sequential pore neutralization, and it manifests itself strongly for divalent ions (e.g.\ Ca$^{2+}$). Ionic Coulomb blockade is closely analogous to electronic Coulomb blockade in quantum dots. In addition to the non-local 1D Coulomb interaction considered in the standard Coulomb blockade approach, we now propose a correction to take account of the singular part of the attraction to the binding site (i.e.\ local site binding). We show that this correction leads to a geometry-dependent shift of one of the barrierless resonant conduction points M$_0^{CB}$. We also show that local ion-ion repulsion accounts for a splitting of Ca$^{2+}$ profiles observed earlier in Brownian dynamics simulations.

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4 pages, 4 figures, 25 references, ICNF2017 Replacement reasons: Some typo are fixed, notation is optimised)
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08 May 2017 14:30
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28 Nov 2020 04:36