Charge fluctuations and their effect on conduction in biological ion channels

TL;DR

This paper investigates how charge and wall fluctuations influence ion channel conductivity, highlighting electrostatic amplification of charge fluctuations as a key factor affecting ion transport.

Contribution

It introduces a Brownian dynamical model incorporating both charge and wall fluctuations, emphasizing the role of electrostatic amplification in channel conductance.

Findings

Charge fluctuations significantly modulate ion channel conductivity.

Wall vibrations influence ion transport both stochastically and periodically.

Electrostatic amplification of charge fluctuations is a leading effect on conduction.

Abstract

The effect of fluctuations on the conductivity of ion channels is investigated. It is shown that modulation of the potential barrier at the selectivity site due to electrostatic amplification of charge fluctuations at the channel mouth exerts a leading-order effect on the channel conductivity. A Brownian dynamical model of ion motion in a channel is derived that takes into account both fluctuations at the channel mouth and vibrational modes of the wall. The charge fluctuations are modeled as a short noise flipping the height of the potential barrier. The wall fluctuations are introduced as a slow vibrational mode of protein motion that modulates ion conductance both stochastically and periodically. The model is used to estimate the contribution of the electrostatic amplification of charge fluctuations to the conductivity of ion channels.