Ab initio investigation of the hydration of deprotonated amino acids.
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.
Michaux
Catherine
C
Laboratoire de Chimie Biologique Structurale, Facultés Universitaires Notre-Dame de la Paix, Namur, Belgium.
Wouters
Johan
J
Perpète
Eric A
EA
Jacquemin
Denis
D
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*
D000596:Amino Acids; D014867:Water; D005973:Glutamine; D001224:Aspartic Acid; D014633:Valine; D000409:Alanine; D019342:Acetic Acid; D005998:Glycine