title: The search for a deterministic origin for the presence of nonracemic amino-acids in meteorites: a computational approach.
abstract: Amino-acid enantiomeric excesses (ee's) have been detected in different types of carbonaceous chondrites, all in favor of the L enantiomer. In this article, we discuss possible deterministic causes to the presence of these amino-acid ee's in meteorites and evaluate in particular enantioselective photolysis by circularly polarized light (CPL). The electronic circular dichroism spectra of a set of amino- and hydroxy-acids, all detected in chondritic matter but some with ee's and others without ee's, were calculated and compared. The spectra were calculated for the most stable conformation(s) of the considered molecules using quantum mechanical methods (density functional theory). Our results suggest that CPL photolysis in the gas phase was perhaps not at the origin of the presence of ee's in meteorites and that the search for another, but still unknown, deterministic cause must be seriously undertaken.
authors.affiliation: Faculty of Applied Sciences, Université libre de Bruxelles, Matières et Matériaux, Brussels, Belgium.
authors.forename: Sophie
authors.initials: S
authors.lastname: Vandenbussche
authors.forename: Jacques
authors.initials: J
authors.lastname: Reisse
authors.forename: Kristin
authors.initials: K
authors.lastname: Bartik
authors.forename: Jacques
authors.initials: J
authors.lastname: Lievin
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D002942:Circular Dichroism; D019110:Meteoroids; D008968:Molecular Conformation; D013237:Stereoisomerism
chemical_list: D000596:Amino Acids