Isotopic evidence for extraterrestrial non- racemic amino acids in the murchison meteorite

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-enantiomers1,2, and the question of why living systems on the Earth consist of L-enantiomers rather than D-enantiomers is unresolved3. A substantial fraction of the organic

compounds on the early Earth may have been derived from comet and meteorite impacts4,5,6. It has been reported previously that amino acids in the Murchison meteorite exhibit an excess of

L-enantiomers7, 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 origin8—rather than a terrestrial overprint of biological amino acids—although reservations have persisted (see, for example, ref. 9).

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. Access through your institution Buy or subscribe This is a preview of subscription content, access

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IN SAMPLES FROM ASTEROID (101955) BENNU Article Open access 29 January 2025 INSIGHTS INTO THE FORMATION AND EVOLUTION OF EXTRATERRESTRIAL AMINO ACIDS FROM THE ASTEROID RYUGU Article Open

access 17 March 2023 PRIMORDIAL AQUEOUS ALTERATION RECORDED IN WATER-SOLUBLE ORGANIC MOLECULES FROM THE CARBONACEOUS ASTEROID (162173) RYUGU Article Open access 10 July 2024 REFERENCES *

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Press, Tucson, (1992). Download references ACKNOWLEDGEMENTS We thank S. Fulkerson for his support of this work, and V. Andrusevich and T.Brockwell for their assistance with the analyses.

This work was supported by the US NSF. Instrument time and travel funds were provided by Micromass Inc. AUTHOR INFORMATION AUTHORS AND AFFILIATIONS * School of Geology and Geophysics, The

University of Oklahoma, Norman, 73019, Oklahoma, USA M. H. Engel * Department of Environmental Sciences, University of Virginia, Charlottesville, 22903, Virginia, USA S. A. Macko Authors *

M. H. Engel View author publications You can also search for this author inPubMed Google Scholar * S. A. Macko View author publications You can also search for this author inPubMed Google

Scholar CORRESPONDING AUTHOR Correspondence to M. H. Engel. RIGHTS AND PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Engel, M., Macko, S. Isotopic evidence for

extraterrestrial non- racemic amino acids in the Murchison meteorite. _Nature_ 389, 265–268 (1997). https://doi.org/10.1038/38460 Download citation * Received: 17 September 1996 * Accepted:

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