COMPUTATIONAL OBSERVATION OF AN ION PERMEATION THROUGH A CHANNEL PROTEIN

The ion permeation process, driven by a membrane potential through an outer membrane protein, OmpF porin of Escherichia coli, was simulated by molecular dynamics. A Nai ion, initially placed in the solvent regi on at the outer side of the porin channel, moved along the electric he ld passing through the porin channel in a 1.3 nsec simulation; the per meation rate was consistent with the experimentally estimated channel activity (10(8)similar to 10(9)/sec). In this simulation, it was indic ated that the ion permeation through the porin channel proceeds by a ' 'push-out'' mechanism, and that Asp113 is an important residue for the channel activity.