The Lancaster Ion Channel Team

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Focus

Main research goals include:

Functionalisation of nanopores

How do the parameters of an artificial nanopore -- radius, length, charge distribution, shape, chemical composition -- affect its conductivity and selectivity? What parameters parameters should is possess in order to demonstrate pre-defined desired properties, or to mimic biological ion channels? We develop theoretical methods to answer these questions.

Ionic Coulomb blockade

A phenomenon of the dramatic decrease of channel's conductance revealed at the specific values of selelectvity filter's charge

More detailed information is provided at the links below.

Projects

Conduction and selectivity between monovalent ions within the potassium channel

We propose to develop a unified theory of conduction through the open potassium (KcsA) channel, taking account of energy quantisation, density of states, charge discreteness, and fluctuations in potential, that were largely ignored in earlier research. Our theory will encompass, as special cases or approximations, several earlier theoretical approaches and will enable us to account for some enduring puzzles and paradoxes of ion channel dynamics, e.g. fast potassium conduction by the potassium channel while discriminating against the (smaller) sodium ion by a factor of more than 1000:1. The results will readily be extendable to other channels and to artificial nanopores.

Ionic Coulomb blockade oscillations and the physical origins of permeation, selectivity, and their mutation transformations in biological ion channels

Brownian dynamic simulations are applied to the model of a Ca channel represented by a dielectric cylinder with a ring of the fixed charge. The Ionic Coulomb blockade (ICB) is a fundamental electrostatic phenomenon based on charge discreteness, electrostatic exclusion principle, and single-file stochastic ion motion through the channel. Anomalous mole fraction effect and valence selectivity are explained. Theoretical findings are tested experimentally using site-directed mutagenesis and patch-clamp studies.

Nonlinear dynamics of selectivity, conductivity, and gating in biological ion channels

We develop a novel Brownian dynamics (BD) description of channels by isolating biologically relevant degrees of freedom using molecular dynamics (MD), and to demonstrate theoretically and numerically that protein vibration, ion size and hydration at the selectivity filter, and charge fluctuations (all largely neglected in earlier work), provide leading order contributions to the channel's high conductivity and selectivity between ions of the same polarity.

Monte Carlo simulations of conductivity in biological ion channels � an exploratory study

As a prototype of a self-consistent approach we suggest to take a system of coupled Poisson and drift diffusion equations that have already been used very successfully in the context of ion channel research. We further suggest to extend the model by adding to it interactions of ions with the vibration of the walls and pair-correlation effect of ionic motion.