  In this paper, we study the selectivity of the potassium channel KcsA by a
recently developed image-charge solvation method(ICSM) combined with molecular
dynamics simulations. The hybrid solvation model in the ICSM is able to
demonstrate atomistically the function of the selectivity filter of the KcsA
channel when potassium and sodium ions are considered and their distributions
inside the filter are simulated. Our study also shows that the reaction field
effect, explicitly accounted for through image charge approximation in the ICSM
model, is necessary in reproducing the correct selectivity property of the
potassium channels.
