Molecular and Brownian dynamics study of ion selectivity and conductivity in the potassium channel

We employ recently revealed structural information for the potassium channel in molecular and Brownian dynamics simulations to investigate the physical mechanisms involved in the transport of ions across this channel. We show that ion selectivity arises from the ability of the channel protein to completely solvate potassium ions but not the smaller sodium ions. From energy and free energy perturbation profiles, we estimate the size of the energy barrier experienced by a sodium ion. Brownian dynamics simulations are carried out to determine conductance properties of this channel under various conditions.