PROTEIN-WATER-ION INTERACTIONS IN A MODEL OF THE PORE DOMAIN OF A POTASSIUM CHANNEL - A SIMULATION STUDY

A model of the selectivity filter of a voltage-gated K+ (Kv) channel f ormed by an eight-stranded P-barrel is compared with physiological pro perties of the channel. Continuum electrostatic calculations suggest t hat only two of the eight Asp sidechains at the extracellular mouth of the pore will ionise. A ring of four Tyr sidechains forms the narrowe st region of the pore. Molecular dynamic simulations of the potential energy of a Kt ion as translated along the model pore indicate that th e two ionised Asp sidechains and the hydroxyl groups of the Tyr sidech ains stabilise the partially desolvated ion as it passes through the n arrowest region. (C) 1998 Elsevier Science B.V.