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Carbon isotope evidence for the substrates and mechanisms of prebiotic synthesis in the early solar system

Chimiak, L. and Elsila, J. E. and Dallas, B. and Dworkin, J. P. and Aponte, J. C. and Sessions, A. L. and Eiler, J. M. (2021) Carbon isotope evidence for the substrates and mechanisms of prebiotic synthesis in the early solar system. Geochimica et Cosmochimica Acta, 292 . pp. 188-202. ISSN 0016-7037. doi:10.1016/j.gca.2020.09.026.

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Meteorites contain prebiotic, bio-relevant organic compounds including amino acids. Their syntheses could result from diverse sources and mechanisms and provide a window on the conditions and materials present in the early solar system. Here we constrain alanine’s synthetic history in the Murchison meteorite using site-specific ¹³C/¹²C measurements, reported relative to the VPDB standard. The δ¹³C_(VPDB) values of −29 ± 10‰, 142 ± 20‰, and −36 ± 20‰ for the carboxyl, amine-bound, and methyl carbons, respectively, are consistent with Strecker synthesis of interstellar-medium-derived aldehydes, ammonia, and low-δ¹³C nebular or interstellar-medium-derived CN. We report experimentally measured isotope effects associated with Strecker synthesis, and use them to constrain the δ¹³C values of the alanine precursors, which we then use to construct a model that predicts the molecular-average δ¹³C values of 19 other organic compounds of prebiotic significance found in Murchison if they were made by our proposed synthetic network. Most of these predictions agree with previous measurements, suggesting that interstellar-medium-derived aldehydes and nebular and/or pre-solar CN could have served as substrates for synthesis of a wide range of prebiotic compounds in the early solar system.

Item Type:Article
Related URLs:
URLURL TypeDescription
Chimiak, L.0000-0002-5047-5421
Dallas, B.0000-0002-1313-3270
Aponte, J. C.0000-0002-0131-1981
Sessions, A. L.0000-0001-6120-2763
Additional Information:© 2020 Published by Elsevier Ltd. Received 27 April 2020, Revised 17 September 2020, Accepted 21 September 2020, Available online 29 September 2020. We would like to acknowledge Dr. Max Klatte and Dr. Carl Blumenfeld for aiding with the Strecker synthesis of alanine. We would also like to acknowledge Thermo Fischer and Caltech for supporting the Caltech center for Isotomics. This project was supported by NASA through LARS grant number NNX17AE52G and through part of the Planetary Science Division Internal Scientist Funding Program through the Fundamental Laboratory Research (FLaRe) work package of the Planetary Science Division Internal Scientist Funding Program, by The Department of Energy through DOE grant DE-SC0016561, and by the Simons Foundations. Author contributions: LC, BD, ALS, and JME designed methods for site-specific carbon isotope measurements. JEE, JPD, and JA provided Murchison sample. JEE extracted amino acids and measured molecular-average isotope ratios of alanine. LC and JME created the Monte Carlo simulation to calculate isotope ratios. LC measured alanine on Murchison meteorite, processed data, and calculated site-specific isotope ratios. LC, JEE, JPD, JA, ALS, and JME contributed ideas to form the parent-body organic synthesis model. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Data and materials availability: All data is available in the main text or the Supplementary Information.
Funding AgencyGrant Number
Department of Energy (DOE)DE-SC0016561
Simons FoundationUNSPECIFIED
Subject Keywords:Meteorite Chemistry; Origins of Life; Strecker Synthesis; Site-Specific Isotope Ratios
Record Number:CaltechAUTHORS:20200930-131626735
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Official Citation:L. Chimiak, J.E. Elsila, B. Dallas, J.P. Dworkin, J.C. Aponte, A.L. Sessions, J.M. Eiler, Carbon isotope evidence for the substrates and mechanisms of prebiotic synthesis in the early solar system, Geochimica et Cosmochimica Acta, Volume 292, 2021, Pages 188-202, ISSN 0016-7037, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:105690
Deposited By: Tony Diaz
Deposited On:30 Sep 2020 20:33
Last Modified:16 Nov 2021 18:45

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