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Drude polarizable force field for cation–π interactions of alkali and quaternary ammonium ions with aromatic amino acid side chains
Author(s) -
Orabi Esam A.,
Davis Rebecca L.,
Lamoureux Guillaume
Publication year - 2020
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.26084
Subject(s) - tetramethylammonium , polarizability , chemistry , molecular dynamics , alkali metal , ion , side chain , tetraethylammonium , computational chemistry , aromaticity , counterion , metal ions in aqueous solution , ammonium , chemical physics , inorganic chemistry , crystallography , molecule , organic chemistry , potassium , polymer
Cation–π interactions play important roles in molecular recognition and in the stability and function of proteins. However, accurate description of the structure and energetics of cation–π interactions presents a challenge to both additive and polarizable force fields, which are rarely designed to account for the complexation of charged groups with aromatic moieties. We calibrate the Drude polarizable force field for complexes of alkali metal ions (Li + , Na + , K + , Rb + , Cs + ), ammonium (NH 4 + ), tetramethylammonium (TMA + ), and tetraethylammonium (TEA + ) with aromatic amino acid side chain model compounds (benzene, toluene, 4‐methylphenol, 3‐methylindole) using high‐level ab initio quantum chemical properties of these complexes. Molecular dynamics simulations reveal that cation–π complexes of the hard and tightly coordinated Li + and Na + ions are not stable in water but that larger ions form stable complexes, with binding free energies ranging between −0.8 and −2.9 kcal/mol. Like in gas phase, all complexes at equilibrium adopt an “en‐face” complexation mode in water. The optimized Drude polarizable model provides an accurate description of the cation–π interactions involving small ions and proteins. © 2019 Wiley Periodicals, Inc.