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Isotopic evidence for extraterrestrial non-racemic amino acids in the Murchison meteorite
- Source :
- Nature. 389(6648)
- Publication Year :
- 1997
-
Abstract
- Many amino acids contain an asymmetric centre, occurring as laevorotatory, L, or dextrorotatory, D, compounds. It is generally assumed that abiotic synthesis of amino acids on the early Earth resulted in racemic mixtures (L- and D-enantiomers in equal abundance). But the origin of life required, owing to conformational constraints, the almost exclusive selection of either L- or D-enantiomers, and the question of why living systems on the Earth consist of L-enantiomers rather than D-enantiomers is unresolved. A substantial fraction of the organic compounds on the early Earth may have been derived from comet and meteorite impacts. It has been reported previously that amino acids in the Murchison meteorite exhibit an excess of L-enantiomers, raising the possibility that a similar excess was present in the initial inventory of organic compounds on the Earth. The stable carbon isotope compositions of individual amino acids in Murchison support an extraterrestrial origin -- rather than a terrestrial overprint of biological amino acids-although reservations have persisted. Here we show that individual amino-acid enantiomers from Murchison are enriched in 15N relative to their terrestrial counterparts, so confirming an extraterrestrial source for an L-enantiomer excess in the Solar System that may predate the origin of life on the Earth.
- Subjects :
- Murchison meteorite
chemistry.chemical_classification
Multidisciplinary
Chromatography, Gas
Extraterrestrial Environment
Chemistry
Stable isotope ratio
Origin of Life
Molecular Conformation
Stereoisomerism
Meteoroids
Early Earth
Gas Chromatography-Mass Spectrometry
Mass Spectrometry
Astrobiology
Amino acid
chemistry.chemical_compound
Meteorite
Isovaline
Isotopes
Chondrite
Abiogenesis
Amino Acids
Subjects
Details
- ISSN :
- 00280836
- Volume :
- 389
- Issue :
- 6648
- Database :
- OpenAIRE
- Journal :
- Nature
- Accession number :
- edsair.doi.dedup.....564c72c423d5360765cb090d499df791