Hydration of chloride anions in the NanC Porin from Escherichia coli: A comparative study by QM/MM and MD simulations

摘要

Chloride anions permeate the bacterial NanC porin in physiological processes. Here we present a DFT-based QM/MM study of this porin in the presence of these anions. Comparison is made with classical MD simulations on the same system. In both QM/MM and classical approaches, the anions are almost entirely solvated by water molecules. However, the average water-Cl-distance is significantly larger in the first approach. Polarization effects of protein groups close to Cl-anion are sizeable. These effects might modulate the anion-protein electrostatic interactions, which in turn play a central role for selectivity mechanisms of the channel. (C) 2014 AIP Publishing LLC.