Abstract:
:A significant portion of prebiotic organic matter on the early Earth may have been introduced by carbonaceous asteroids and comets. The distribution and stable-isotope composition of individual organic compounds in carbonaceous meteorites, which are thought to be derived from asteroidal parent bodies, may therefore provide important information concerning mechanistic pathways for prebiotic synthesis and the composition of organic matter on Earth before living systems developed. Previous studies have shown that meteorite amino acids are enriched in 13C relative to their terrestrial counterparts, but individual species were not distinguished. Here we report the 13C contents of individual amino acids in the Murchison meteorite. The amino acids are enriched in 13C, indicating an extraterrestrial origin. Alanine is not racemic, and the 13C enrichment of its D- and L-enantiomers implies that the excess of the L-enantiomer is indigenous rather than terrestrial contamination, suggesting that optically active materials were present in the early Solar System before life began.
journal_name
Naturejournal_title
Natureauthors
Engel MH,Macko SA,Silfer JAdoi
10.1038/348047a0keywords:
subject
Has Abstractpub_date
1990-11-01 00:00:00pages
47-9issue
6296eissn
0028-0836issn
1476-4687journal_volume
348pub_type
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