Theoretical study on the water structure of the aqueous amino acid solutions using Monte Carlo method.

Abstract

Abstract Series of canonical ensemble Monte Carlo simulations are carried out at 298K to study the role of water-amino acid interactions in determining solvent water structure. Each simulation box is composed of 222 water molecules and one amino acid zwitterion such as Alanine(Ala), Tyrosine(Tyr), Serine(Ser), Asparagine (Asn) and Aspartate(Asp). Thermodynamic properties and some structural properties are obtained by ensemble averaging during the simulations. Special interests are focused on the analysis of radial distribution functions and four, five, six and seven- membered ring structures connected via hydrogen bonds of solvent water molecules surrounding each amino acids. The hydrophilicity of an amino acid is found to be closely related to the characteristic of hydrogen bond distributions. Especially, the number of topological 6 and 7-membered ring structures increases as the hydrophilicity of an amino acid increases.