Bucher, DenisGuidoni, LeonardoCarloni, PaoloRothlisberger, Ursula2011-12-162011-12-162011-12-16201010.1016/j.bpj.2010.01.064https://infoscience.epfl.ch/handle/20.500.14299/75520WOS:000277858400001Quantum mechanics/molecular mechanics (QM/MM) Car-Parrinello simulations were performed to estimate the coordination numbers of K+ and Na+ ions in the selectivity filter of the KcsA channel, and in water. At the DFT/BLYP level, K+ ions were found to display an average coordination number of 6.6 in the filter, and 6.2 in water. Na+ ions displayed an average coordination number of 5.2 in the filter, and 5.0 in water. A comparison was made with the average coordination numbers obtained from using classical molecular dynamics (6.7 for K+ in the filter, 6.6 for K+ in water, 6.0 for Na+ in the filter, and 5.2 for Na+ in water). The observation that different coordination numbers were displayed by the ions in QM/MM simulations and in classical molecular dynamics is relevant to the discussion of selectivity in K-channels.Aqueous-SolutionsTopological ControlHydrationSimulationSolvationPolarizationBindingDensityWatertext::journal::journal article::research article