Anisotropic solvent model of the lipid bilayer. 1. Parameterization of long-range electrostatics and first solvation shell effects.

ABSTRACT: A new implicit solvation model was developed for calculating free energies of transfer of molecules from water to any solvent with defined bulk properties. The transfer energy was calculated as a sum of the first solvation shell energy and the long-range electrostatic contribution. The first term was proportional to solvent accessible surface area and solvation parameters (?(i)) for different atom types. The electrostatic term was computed as a product of group dipole moments and dipolar solvation parameter (?) for neutral molecules or using a modified Born equation for ions. The regression coefficients in linear dependencies of solvation parameters ?(i) and ? on dielectric constant, solvatochromic polarizability parameter ?*, and hydrogen-bonding donor and acceptor capacities of solvents were optimized using 1269 experimental transfer energies from 19 organic solvents to water. The root-mean-square errors for neutral compounds and ions were 0.82 and 1.61 kcal/mol, respectively. Quantification of energy components demonstrates the dominant roles of hydrophobic effect for nonpolar atoms and of hydrogen-bonding for polar atoms. The estimated first solvation shell energy outweighs the long-range electrostatics for most compounds including ions. The simplicity and computational efficiency of the model allows its application for modeling of macromolecules in anisotropic environments, such as biological membranes.

SUBMITTER: Lomize AL 

PROVIDER: S-EPMC3089899 | biostudies-literature | 2011 Apr

REPOSITORIES: biostudies-literature