Unusual nonterrestrial l‐proteinogenic amino acid excesses in the Tagish Lake meteorite

Abstract

Abstract-The distribution and isotopic and enantiomeric compositions of amino acids found in three distinct fragments of the Tagish Lake C2-type carbonaceous chondrite were investigated via liquid chromatography with fluorescence detection and time-of-flight mass spectrometry and gas chromatography isotope ratio mass spectrometry. Large l-enantiomeric excesses (l ee 43-59%) of the a-hydrogen aspartic and glutamic amino acids were measured in Tagish Lake, whereas alanine, another a-hydrogen protein amino acid, was found to be nearly racemic (d l) using both techniques. Carbon isotope measurements of d-and l-aspartic acid and d-and l-alanine in Tagish Lake fall well outside of the terrestrial range and indicate that the measured aspartic acid enantioenrichment is indigenous to the meteorite. Alternate explanations for the l-excesses of aspartic acid such as interference from other compounds present in the sample, analytical biases, or terrestrial amino acid contamination were investigated and rejected. These results can be explained by differences in the solid-solution phase behavior of aspartic acid, which can form conglomerate enantiopure solids during crystallization, and alanine, which can only form racemic crystals. Amplification of a small initial l-enantiomer excess during aqueous alteration on the meteorite parent body could have led to the large l-enrichments observed for aspartic acid and other conglomerate amino acids in Tagish Lake. The detection of nonterrestrial l-proteinogenic amino acid excesses in the Tagish Lake meteorite provides support for the hypothesis that significant enantiomeric enrichments for some amino acids could form by abiotic processes prior to the emergence of life.

Ultraviolet to near-infrared spectroscopy of the potentially hazardous, low delta-V asteroid (175706) 1996 FG3

“…Its mineralogical and chemical properties are between those of CM and CI meteorites, and its high microporosity (∼40%) makes it a good candidate material for the composition of low bulk density primitive asteroids (e.g., Brown et al 2000;Hildebrand et al 2006). Moreover, nonterrestrial L-proteinogenic amino acid excesses have been detected in this meteorite, strengthening the hypothesis that primitive minor bodies could have delivered enantiomerically enriched amino acids to the early Earth that could have triggered the emergence of life (Glavin et al 2012). If confirmed, a link with the Tagish Lake meteorite would be fascinating, and would confirm the very primitive nature of 1996 FG3, in agreement with the results by Rivkin et al (2013).…”

Verfahren zur Enantiomerentrennung

“…B. Lit. [2][3][4][5]). Unabhängig davon besteht wachsendes Interesse an der Erzeugung reiner Enantiomere in den Bereichen der Life Sciences, wie der Lebensmittel-und der agrochemischen Industrie sowie insbesondere in der pharmazeutischen Industrie.…”

Photosynthesis and Photo-Stability of Nucleic Acids in Prebiotic Extraterrestrial Environments

“…There is ample evidence that many of these materials are truly extraterrestrial, and not terrestrial contamination. For example, the extraterrestrial nature of the many amino acids detected in meteorites is supported by the presence of (i) amino acids not used by biological systems on Earth, (ii) amino acids that are largely (but not entirely) racemic, and (iii) amino acids having non-terrestrial isotopic ratios (Engel and Macko 1997;Pizzarello 1997, 1999;Pizzarello and Huang 2003;Martins et al 2007;Glavin et al 2012;Callahan et al 2013). …”