| Trans-membrane potassium channels permit the flux of potassium ions out of neurons and are critical to the propagation of electrical signals through the central nervous system. The dynamic nature of potassium channels is crucial for determining the fundamentals of ion permeation (i.e. accounting for the high rate of ion flow out of the cell and the selectivity for K+ over other ionic species).; At each position of the ion, a simulation is performed and the motions of and forces on the surrounding water, ions and particular protein atoms are monitored.; The translation of the ion through the cavity of the potassium ion channel is driven primarily by its attractive interactions with the protein and the solvent until the ion is at the base of the selectivity filter where it is repelled by Van der Waals interactions with the protein. The ion is fully-hydrated with an average K+-O distance of 2.90 A. (Abstract shortened by UMI.)... |
