Extraterrestrial amino acids and L‐enantiomeric excesses in the CM2 carbonaceous chondrites Aguas Zarcas and Murchison

The abundances, distributions, enantiomeric ratios, and carbon isotopic compositions of amino acids in two fragments of the Aguas Zarcas CM2 type carbonaceous chondrite fall and a fragment of the CM2 Murchison meteorite were determined via liquid chromatography time‐of‐flight mass spectrometry and g...

Full description

Saved in:
Bibliographic Details
Published in:Meteoritics & planetary science 2021-01, Vol.56 (1), p.148-173
Main Authors: Glavin, Daniel P., Elsila, Jamie E., McLain, Hannah L., Aponte, José C., Parker, Eric T., Dworkin, Jason P., Hill, Dolores H., Connolly, Harold C., Lauretta, Dante S.
Format: Article
Language:English
Subjects:
Abundance
Alanine
Amino acids
Carbon
Carbon 13
Carbon isotopes
Carbonaceous chondrites
Chondrites
Chromatography
Circular polarization
Contamination
Crystals
Fragments
Gas chromatography
Glutamic acid
Isotope composition
Isotope ratios
Isotopes
Liquid chromatography
Mass spectrometry
Meteorites
Meteors & meteorites
Murchison meteorite
Origin of life
Polarized light
Proteins
Scientific imaging
Solar system
Solar system evolution
Spectroscopy
Terrestrial environments
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The abundances, distributions, enantiomeric ratios, and carbon isotopic compositions of amino acids in two fragments of the Aguas Zarcas CM2 type carbonaceous chondrite fall and a fragment of the CM2 Murchison meteorite were determined via liquid chromatography time‐of‐flight mass spectrometry and gas chromatography isotope ratio mass spectrometry. A suite of two‐ to six‐carbon aliphatic primary amino acids was identified in the Aguas Zarcas and Murchison meteorites with abundances ranging from ~0.1 to 158 nmol/g. The high relative abundances of α‐amino acids found in these meteorites are consistent with a Strecker‐cyanohydrin synthesis on these meteorite parent bodies. Amino acid enantiomeric and carbon isotopic measurements in both fragments of the Aguas Zarcas meteorites indicate that both samples experienced some terrestrial protein amino acid contamination after their fall to Earth. In contrast, similar measurements of alanine in Murchison revealed that this common protein amino acid was both racemic (D ≈ L) and heavily enriched in 13C, indicating no measurable terrestrial alanine contamination of this meteorite. Carbon isotope measurements of two rare non‐proteinogenic amino acids in the Aguas Zarcas and Murchison meteorites, α‐aminoisobutyric acid and D‐ and L‐isovaline, also fall well outside the typical terrestrial range, confirming they are extraterrestrial in origin. The detections of non‐terrestrial L‐isovaline excesses of ~10–15% in both the Aguas Zarcas and Murchison meteorites, and non‐terrestrial L‐glutamic acid excesses in Murchison of ~16–40% are consistent with preferential enrichment of circularly polarized light generated L‐amino acid excesses of conglomerate enantiopure crystals during parent body aqueous alteration and provide evidence of an early solar system formation bias toward L‐amino acids prior to the origin of life.
ISSN:1086-9379
1945-5100
DOI:10.1111/maps.13451