Potential of mean force between two ions in a sucrose rich aqueous solution

Molecular dynamics and potential of mean force (PMF) calculations are perfo rmed on an aqueous sucrose solution of an ion pair to investigate how ionic interactions are modified by the presence of the sugar. The presence of su crose is shown to deepen the PMF minimum for Na-Cl ion pair, with an overal l behavior compatible with continuum electrostatics. The comparison of PMF and hydration of the Na-Cl ion pair in pure water and in concentrated aqueo us sucrose solution clearly reveals the preferential hydration of ions. The relevance of these results to biological systems is discussed. (C) 2000 El sevier Science B.V. All rights reserved.