The abundances, distributions, enantiomeric ratios, and carbon isotopic compositions of amino acids in two fragments of the Aguas Zarcas CM2 type carbonaceous chondrite fall and a fragment of the CM2 Murchison meteorite were determined via liquid chromatography time-of-flight mass spectrometry and gas chromatography isotope ratio mass spectrometry. A suite of twoto six-carbon aliphatic primary amino acids was identified in the Aguas Zarcas and Murchison meteorites with abundances ranging from ~0.1 to 158 nmol/g. The high relative abundances of a-amino acids found in these meteorites are consistent with a Strecker-cyanohydrin synthesis on these meteorite parent bodies. Amino acid enantiomeric and carbon isotopic measurements in both fragments of the Aguas Zarcas meteorites indicate that both samples experienced some terrestrial protein amino acid contamination after their fall to Earth. In contrast, similar measurements of alanine in Murchison revealed that this common protein amino acid was both racemic (D L) and heavily enriched in C, indicating no measurable terrestrial alanine contamination of this meteorite. Carbon isotope measurements of two rare nonproteinogenic amino acids in the Aguas Zarcas and Murchison meteorites, aaminoisobutyric acid and Dand L-isovaline, also fall well outside the typical terrestrial range, confirming they are extraterrestrial in origin. The detections of non-terrestrial Lisovaline excesses of ~10–15% in both the Aguas Zarcas and Murchison meteorites, and non-terrestrial L-glutamic acid excesses in Murchison of ~16–40% are consistent with preferential enrichment of circularly polarized light generated L-amino acid excesses of conglomerate enantiopure crystals during parent body aqueous alteration and provide evidence of an early solar system formation bias toward L-amino acids prior to the origin of life.

中文翻译：

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CM2 碳质球粒陨石 Aguas Zarcas 和 Murchison 中的外星氨基酸和 L-对映体过量

Aguas Zarcas CM2型碳质球粒陨石落的两个碎片和CM2 Murchison陨石的一个碎片中氨基酸的丰度、分布、对映体比率和碳同位素组成通过液相色谱飞行时间质谱和气相色谱测定同位素比质谱法。在 Aguas Zarcas 和 Murchison 陨石中鉴定出一组二至六碳脂肪族初级氨基酸，丰度范围为~0.1 至 158 nmol/g。在这些陨石中发现的高相对丰度的 a-氨基酸与这些陨石母体上的 Strecker-氰醇合成一致。Aguas Zarcas 陨石的两个碎片中的氨基酸对映体和碳同位素测量表明，这两个样本在落到地球后都经历了一些陆地蛋白质氨基酸污染。相比之下，默奇森中丙氨酸的类似测量表明，这种常见的蛋白质氨基酸既是外消旋的 (DL)，又富含 C，表明这颗陨石没有可测量的陆地丙氨酸污染。Aguas Zarcas 和 Murchison 陨石中两种罕见的非蛋白质氨基酸，氨基异丁酸和 Dand L-异缬氨酸的碳同位素测量值也远远超出了典型的地球范围，证实它们起源于外星。在 Aguas Zarcas 和 Murchison 陨石中检测到约 10-15% 的非地球 Lisovaline 过量，