Epstein S, Krishnamurthy R V, Cronin J R, Pizzarello S, Yuen G U
Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena 91125, USA.
Nature. 1987 Apr 2;326(6112):477-9. doi: 10.1038/326477a0.
Much effort has been directed to analyses of organic compounds in carbonaceous chondrites because of their implications for organic chemical evolution and the origin of life. We have determined the isotopic composition of hydrogen, nitrogen and carbon in amino acid and monocarboxylic acid extracts from the Murchison meteorite. The unusually high D/H and 15N/14N ratios in the amino acid fraction (delta D = 1,370% after correction for isotope exchange; delta 15N = 90) are uniquely characteristic of known interstellar organic materials. The delta D value of the monocarboxylic acid fraction is lower (377%), but still consistent with an interstellar origin. These results confirm the extraterrestrial origin of both classes of compound, and provide the first evidence suggesting a direct relationship between the massive organo-synthesis occurring in interstellar clouds and the presence of pre-biotic compounds in primitive planetary bodies. The isotope data also bear on the historical problem of distinguishing indigenous material from terrestrial contaminants.
由于碳质球粒陨石中的有机化合物对有机化学演化和生命起源具有重要意义，人们对其进行了大量研究。我们测定了默奇森陨石氨基酸和单羧酸提取物中氢、氮和碳的同位素组成。氨基酸部分异常高的D/H和15N/14N比值（校正同位素交换后δD = 1370‰；δ15N = 90）是已知星际有机物质的独特特征。单羧酸部分的δD值较低（377‰），但仍与星际起源一致。这些结果证实了这两类化合物的地外起源，并首次提供了证据，表明星际云中发生的大规模有机合成与原始行星体中益生元化合物的存在之间存在直接关系。同位素数据也与区分原生物质和地球污染物这一历史问题相关。
