Extraterrestrial amino acids identified in metal-rich CH and CB carbonaceous chondrites from Antarctica
Article first published online: 19 FEB 2013
© The Meteoritical Society, 2013.
Meteoritics & Planetary Science
Volume 48, Issue 3, pages 390–402, March 2013
How to Cite
Burton, A. S., Elsila, J. E., Hein, J. E., Glavin, D. P. and Dworkin, J. P. (2013), Extraterrestrial amino acids identified in metal-rich CH and CB carbonaceous chondrites from Antarctica. Meteoritics & Planetary Science, 48: 390–402. doi: 10.1111/maps.12063
- Issue published online: 18 MAR 2013
- Article first published online: 19 FEB 2013
- Manuscript Accepted: 6 DEC 2012
- Manuscript Received: 3 AUG 2012
- NASA Postdoctoral Program fellowship
- National Aeronautics and Space Administration (NASA) Astrobiology Institute and the Goddard Center for Astrobiology and the NASA Cosmochemistry and Exobiology Programs
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 (CH3), Pecora Escarpment (PCA) 91467 (CH3), Patuxent Range (PAT) 91546 (CH3), MacAlpine Hills (MAC) 02675 (CBb), 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 δ13C/12C 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.