Stability of Positively Charged Solutes in Water: A Transition from Hydrophobic to Hydrophilic
Tod A Pascal, Shiang-Tai Lin, William Goddard, III, and Yousung Jung
J. Phys. Chem. Lett., 2012, 3 (3), pp 294–298
Publication Date (Web): January 7, 2012
Copyright © 2012 American Chemical Society
To improve the description of solvation thermodynamics of biomolecules, we report here the dependence of solvation on the curvature and surface charge of positively charged solutes in water based on extensive molecular dynamics simulations analyzed using the two-phase thermodynamic method. At a surface charge of +0.4e, the compensating forces of favorable electrostatic stabilization and entropic destabilization cancel almost exactly, representing a molecular crossover point from hydrophobic to hydrophilic behavior, independent of curvature. These results suggest that one should include charge-dependent entropic corrections to continuum models aimed at predicting the solvation free energies of large biomolecules.
Keywords: molecular dynamics; free-energy simulations; interfacial effects; electrostatics; surface tension
For further details: http://pubs.acs.org/doi/abs/10.1021/jz201612y