title: Eutectic formation analysis of amino acid mixtures using molecular dynamics simulations.
abstract: The mechanism of eutectic formation was investigated via computer-aided molecular dynamics techniques based on experimental results. The CBZ group mixtures CBZ-l-Asp/d-AlaNH2 x HCl/methanol, CBZ-l-Asp/l-PheOMe x HCl/methanol, and CBZ-l-Tyr/l-ArgNH2 x 2HCl/methanol formed transparent eutectic melts. The non-CBZ group mixtures l-Asp/d-AlaNH2 x HCl/methanol, l-Asp/l-PheOMe x HCl/methanol, and l-Tyr/l-ArgNH2 x 2HCl/methanol did not form eutectic melts. According to molecular dynamics simulation results, increase in the kinetic energy values of eutectic forming mixtures was much larger than the increase in potential energy over a temperature shift from 298 to 333 K. However, the results for non-eutectic forming mixtures were reversed. The Coulomb interaction energies of eutectic forming mixtures significantly decreased, because eutectic melting can increase the mobility of molecules in the mixtures. The enhancement of molecular mobility was confirmed by increased self-diffusion constant values, and the change of solid-to-liquid phase was detected by radial distribution function results. The periodic boundary conditions for calculation of molecular dynamics were found to be reliable.
authors.affiliation: Department of Biotechnology, College of Engineering, Yonsei University, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-749, South Korea.
authors.forename: Hyun Jung
authors.initials: HJ
authors.lastname: Kim
authors.forename: Jong Hoon
authors.initials: JH
authors.lastname: Kim
authors.forename: Sung Hun
authors.initials: SH
authors.lastname: Youn
authors.forename: Chul Soo
authors.initials: CS
authors.lastname: Shin
mesh_terms: D000409:Alanine / Q000031:analogs & derivatives / Q000737:chemistry; D000596:Amino Acids / Q000737:chemistry*; D001224:Aspartic Acid / Q000737:chemistry; D003198:Computer Simulation; D008956:Models, Chemical; D015203:Reproducibility of Results; D014443:Tyrosine / Q000737:chemistry
chemical_list: D000596:Amino Acids; C086275:N-carbobenzyloxyalanine; D001224:Aspartic Acid; D014443:Tyrosine; D000409:Alanine