title: The fate of amino acids during simulated meteoritic impact.
abstract: Delivery of prebiotic molecules, such as amino acids and peptides, in meteoritic/micrometeoritic materials to early Earth during the first 500 million years is considered to be one of the main processes by which the building blocks of life arrived on Earth. In this context, we present a study in which the effects of impact shock on amino acids and a peptide in artificial meteorites composed of saponite clay were investigated. The samples were subjected to pressures ranging from 12-28.9 GPa, which simulated impact velocities of 2.4-5.8 km/s for typical silicate-silicate impacts on Earth. Volatilization was determined by weight loss measurement, and the amino acid and peptide response was analyzed by gas chromatography-mass spectrometry. For all compounds, degradation increased with peak pressure. At the highest shock pressures, amino acids with an alkyl side chain were more resistant than those with functional side chains. The peptide cleaved into its two primary amino acids. Some chiral amino acids experienced partial racemization during the course of the experiment. Our data indicate that impact shock may act as a selective filter to the delivery of extraterrestrial amino acids via carbonaceous chondrites.
authors.affiliation: Centre de Biophysique Moléculaire-CNRS affiliated with the University of Orléans, 45071 Orléans, France. marylene.bertrand@cnrs-orleans.fr
authors.forename: Marylène
authors.initials: M
authors.lastname: Bertrand
authors.forename: Sjerry
authors.initials: S
authors.lastname: van der Gaast
authors.forename: Faith
authors.initials: F
authors.lastname: Vilas
authors.forename: Friedrich
authors.initials: F
authors.lastname: Hörz
authors.forename: Gerald
authors.initials: G
authors.lastname: Haynes
authors.forename: Annie
authors.initials: A
authors.lastname: Chabin
authors.forename: Andre
authors.initials: A
authors.lastname: Brack
authors.forename: Frances
authors.initials: F
authors.lastname: Westall
mesh_terms: D000596:Amino Acids / Q000032:analysis* / Q000737:chemistry*; D004151:Dipeptides / Q000032:analysis / Q000737:chemistry; D008401:Gas Chromatography-Mass Spectrometry; D019110:Meteoroids; D011312:Pressure; D013237:Stereoisomerism; D014835:Volatilization
chemical_list: D000596:Amino Acids; D004151:Dipeptides