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Extraterrestrial amino acids identified in metal‐rich CH and CB carbonaceous chondrites from Antarctica
Author(s) -
Burton Aaron S.,
Elsila Jamie E.,
Hein Jason E.,
Glavin Daniel P.,
Dworkin Jason P.
Publication year - 2013
Publication title -
meteoritics and planetary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.09
H-Index - 100
eISSN - 1945-5100
pISSN - 1086-9379
DOI - 10.1111/maps.12063
Subject(s) - chondrite , chemistry , carbonaceous chondrite , amino acid , mass spectrometry , meteorite , astrobiology , chromatography , biochemistry , biology
Carbonaceous chondrites contain numerous indigenous organic compounds and could have been an important source of prebiotic compounds required for the origin of life on Earth or elsewhere. Extraterrestrial amino acids have been reported in five of the eight groups of carbonaceous chondrites and are most abundant in CI , CM , and CR chondrites but are also present in the more thermally altered CV and CO chondrites. We report the abundance, distribution, and enantiomeric and isotopic compositions of simple primary amino acids in six metal‐rich CH and CB carbonaceous chondrites that have not previously been investigated for amino acids: Allan Hills (ALH) 85085 ( CH 3), Pecora Escarpment (PCA) 91467 ( CH 3), Patuxent Range (PAT) 91546 ( CH 3), MacAlpine Hills (MAC) 02675 ( CB b), Miller Range (MIL) 05082 ( CB ), and Miller Range (MIL) 07411 ( CB ). Amino acid abundances and carbon isotopic values were obtained by using both liquid chromatography time‐of‐flight mass spectrometry and fluorescence, and gas chromatography isotope ratio mass spectrometry. The δ 13 C/ 12 C ratios of multiple amino acids fall outside of the terrestrial range and support their extraterrestrial origin. Extracts of CH chondrites were found to be particularly rich in amino acids (13–16 parts per million, ppm) while CB chondrite extracts had much lower abundances (0.2–2 ppm). The amino acid distributions of the CH and CB chondrites were distinct from the distributions observed in type 2 and 3 CM and CR chondrites and contained elevated levels of β‐, γ‐, and δ‐amino acids compared to the corresponding α‐amino acids, providing evidence that multiple amino acid formation mechanisms were important in CH and CB chondrites.