| タイトル | Unusual Nonterrestrial L-proteinogenic Amino Acid excesses in the Tagish Lake Meteorite |
| 著者（英） | Glavin, Daniel P.; Dworkin, Jason P.; Elsila, Jamie E.; Hilts, Robert W.; Callahan, Michael P.; Herd, D. K.; Burton, Aaron S. |
| 著者所属（英） | NASA Goddard Space Flight Center |
| 発行日 | 2012-08-01 |
| 言語 | eng |
| 内容記述 | 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(sub ee) approximately 43-59%) of the alpha-hydrogen aspartic and glutamic amino acids were measured in Tagish Lake, whereas alanine, another alpha hydrogen protein amino acid, was found to be nearly racemic (D much approximately L) using both techniques. Carbon isotope measurements of D- and L-aspartic acid and 1)- 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 non terrestrial 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. |
| NASA分類 | Lunar and Planetary Science and Exploration |
| レポートNO | GSFC.JA.6869.2012 |
| 権利 | Copyright |
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