The evolution of amino acids under asteroidal aqueous alteration

作者：Yingying He, Samuel Bernard, Marceau Lecasble, Jean‐Christophe Viennet, I. Criouet, David Boulesteix, Nadezda Khodorova, Ludovic Delbes, Maxime Guillaumet, François Baudin, Boris Laurent, A. Buch, Laurent Rémusat · 发表于：Geochimica et Cosmochimica Acta · 年份：2024 · DOI：10.1016/j.gca.2024.09.035 · 被引用次数：8 · 研究领域：Astro and Planetary Science、Origins and Evolution of Life、Isotope Analysis in Ecology

Carbonaceous chondrites contain amino acids , with variable abundances and isotope compositions between and within carbonaceous chondrites . The parent body processes, and the presence of clay minerals may explain those differences. Here, we experimentally investigate the evolution of 6 amino acids (glycine, β-alanine, α-alanine, 2-aminoisobutyric acid, γ-aminobutyric acid, and isovaline) exposed to hydrothermal conditions in the presence or absence of silicates. We determined the chemical nature and isotopic composition of the organic compounds of the soluble and solid fractions of the residues using X-ray diffraction, spectroscopy, and mass-spectrometry methods. Glycine and α-alanine exhibit a rather high stability, which is consistent with the measured abundances of α-alanine and glycine in chondrites having experienced various degrees of aqueous alteration. In the meantime, the evolution of β-alanine under hydrothermal conditions leads to the formation of a new compound, which likely results from the decarboxylation and deamination of β-alanine followed by recombination. More than 95 % of γ-ABA was transformed into 2-pyrrolidione though self-cyclization during the aqueous alteration. The solid residues of the experiments conducted in the presence of clay minerals contain organic material, with abundances varying depending on the amino acid used for the experiments (TOC isovaline > 2-aminoisobutyric acid > γ-aminobutyric acid > glycine > α-alanine > β-alanine). Clay minera...