title: Ab initio investigation of the hydration of deprotonated amino acids.
abstract: The complexation of five deprotonated anionic amino acids (glycine, L-alanine, L-valine, L-Aspartic acid, and L-glutamine) with one water molecule, has been investigated using a MP2/63-11++G(d,p) approach fully accounting for the basis set superposition errors. For each amino acid, several energetic minima have been identified, and we provide spectroscopic information allowing to discriminate them. Our results strongly suggest that two complexes should coexist under the experimental conditions for [Ala - H](-), [Val - H](-), and [Asp - H](-). Comparisons with the experimental enthalpies, entropies, and Gibbs free energies recently obtained by Wincel [J. Am. Soc. Mass Spectrom. 2008, 19, 1091-1097] show that our simulation reproduces the most significant structure/energy experimental trends, though the entropic changes induced by hydration are slightly overestimated.
authors.affiliation: Laboratoire de Chimie Biologique Structurale, Facultés Universitaires Notre-Dame de la Paix, Namur, Belgium.
authors.forename: Catherine
authors.initials: C
authors.lastname: Michaux
authors.forename: Johan
authors.initials: J
authors.lastname: Wouters
authors.forename: Eric A
authors.initials: EA
authors.lastname: Perpète
authors.forename: Denis
authors.initials: D
authors.lastname: Jacquemin
mesh_terms: D019342:Acetic Acid / Q000737:chemistry; D000409:Alanine / Q000737:chemistry; D000596:Amino Acids / Q000737:chemistry*; D001224:Aspartic Acid / Q000737:chemistry; D003198:Computer Simulation; D005973:Glutamine / Q000737:chemistry; D005998:Glycine / Q000737:chemistry; D013058:Mass Spectrometry; D008958:Models, Molecular; D013816:Thermodynamics; D014633:Valine / Q000737:chemistry; D014867:Water / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D014867:Water; D005973:Glutamine; D001224:Aspartic Acid; D014633:Valine; D000409:Alanine; D019342:Acetic Acid; D005998:Glycine