title: 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 (σ(i)) for different atom types. The electrostatic term was computed as a product of group dipole moments and dipolar solvation parameter (η) for neutral molecules or using a modified Born equation for ions. The regression coefficients in linear dependencies of solvation parameters σ(i) and η on dielectric constant, solvatochromic polarizability parameter π*, 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.
authors: Department of Medicinal Chemistry, College of Pharmacy, University of Michigan , 428 Church St., Ann Arbor, Michigan 48109-1065, USA. almz@umich.edu
authors: Andrei L
authors: AL
authors: Lomize
authors: Irina D
authors: ID
authors: Pogozheva
authors: Henry I
authors: HI
authors: Mosberg
mesh_terms: D000465:Algorithms; D016880:Anisotropy; D002462:Cell Membrane / Q000737:chemistry; D003198:Computer Simulation; D004735:Energy Transfer; D006860:Hydrogen Bonding; D008051:Lipid Bilayers / Q000737:chemistry*; D046911:Macromolecular Substances; D008962:Models, Theoretical; D012996:Solutions / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D055672:Static Electricity; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
chemical_list: D008051:Lipid Bilayers; D046911:Macromolecular Substances; D012996:Solutions; D012997:Solvents; D014867:Water