Publications

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Book Chapter
Glavin, DP, Matrajt G, Bada JL.  2004.  Re-examination of amino acids in Antarctic micrometeorites. Space Life Sciences: Steps toward Origin(S) of Life. 33( Bernstein MP, Kress M, NavarroGonzalez R, Eds.).:106-113., Kidlington: Pergamon-Elsevier Science Ltd   10.1016/j.asr.2003.02.011   Abstract

The delivery of amino acids by micrometeorites to the early Earth during the period of heavy bombardment (4.5-3.5 Ga) could have been a significant source of the Earth's prebiotic organic inventory. Antarctic micrometeorites (AMMs) in the 100-200 mum size range represent the dominant mass fraction of extraterrestrial material accreted by the Earth today. However, one problem is that these 'large' micrometeorite grains can be heated to very high temperatures (1000 to 1500 degreesC) during atmospheric deceleration, causing the amino acids to decompose. In this study, we have analyzed the acid-hydrolyzed, hot water extracts from 455 AMMs for the presence of amino acids using high performance liquid chromatography. For comparison, a 5 mg sample of the CM meteorite Murchison was also investigated. In the Murchison sample we found high levels (similar to3-4 parts-per-million, ppm) of alpha-aminoisobutyric acid (AIB) and isovaline, two non-protein amino acids that are extremely rare on Earth and are characteristic of amino acids of apparent extraterrestrial origin. In contrast, we were unable to detect any AIB above the 0.1 ppm level in the AMM samples studied. Only in one AMM sample from a previous study has AIB been detected (similar to300 ppm). To date, more than 600 AMMs have been analyzed for extraterrestrial amino acids. Although our results indicate that less than 5% of all AMMs contain detectable levels of AIB, we cannot rule out the possibility that AIB can be delivered to the Earth intact by a small percentage of AMMs that escaped extensive heating during atmospheric entry. (C) 2003 COSPAR. Published by Elsevier Ltd. All rights reserved.

Journal Article
Glavin, DP, Aubrey AD, Callahan MP, Dworkin JP, Elsila JE, Parker ET, Bada JL, Jenniskens P, Shaddad MH.  2010.  Extraterrestrial amino acids in the Almahata Sitta meteorite. Meteoritics & Planetary Science. 45:1695-1709.   10.1111/j.1945-5100.2010.01094.x   AbstractWebsite

Amino acid analysis of a meteorite fragment of asteroid 2008 TC(3) called Almahata Sitta was carried out using reverse-phase liquid chromatography coupled with UV fluorescence detection and time-of-flight mass spectrometry (LC-FD/ToF-MS) as part of a sample analysis consortium. LC-FD/ToF-MS analyses of hot-water extracts from the meteorite revealed a complex distribution of two- to seven-carbon aliphatic amino acids and one- to three-carbon amines with abundances ranging from 0.5 to 149 parts-per-billion (ppb). The enantiomeric ratios of the amino acids alanine, beta-amino-n-butyric acid, 2-amino-2-methylbutanoic acid (isovaline), and 2-aminopentanoic acid (norvaline) in the meteorite were racemic (d/l similar to 1), indicating that these amino acids are indigenous to the meteorite and not terrestrial contaminants. Several other nonprotein amino acids were also identified in the meteorite above background levels including alpha-aminoisobutyric acid (alpha-AIB), 4-amino-2-methylbutanoic acid, 4-amino-3-methylbutanoic acid, and 3-, 4-, and 5-aminopentanoic acid. The total abundances of isovaline and alpha-AIB in Almahata Sitta are approximately 1000 times lower than the abundances of these amino acids found in the CM carbonaceous chondrite Murchison. The extremely low abundances and unusual distribution of five-carbon amino acids in Almahata Sitta compared to CI, CM, and CR carbonaceous chondrites may reflect extensive thermal alteration of amino acids on the parent asteroid by partial melting during formation or subsequent impact shock heating. It is also possible that amino acids were synthesized by catalytic reactions on the parent body after asteroid 2008 TC(3) cooled to lower temperatures, or introduced as a contaminant from unrelated meteorite clasts and chemically altered by alpha-decarboxylation.

Wing, MR, Bada JL.  1992.  The Origin of the Polycyclic Aromatic-Hydrocarbons in Meteorites. Origins of Life and Evolution of the Biosphere. 21:375-383. AbstractWebsite

Polycyclic aromatic hydrocarbons (PAHs) in Cl and C2 Carbonaceous Chondrites appear to be the product of a high-temperature synthesis. This observation counters a prevailing view that PAHs in meteorites are a thermal alternation product of preexisting aliphatic compounds, which in turn required the presence of low-temperature mineral phases such as magnetite and hydrated phyllosilicates for their formation. Such a process would necessarily lead to a more low-temperature assemblage of PAHs, as many low-temperature minerals and compounds are extant in meteorites. Ivuna, a C1 carbonaceous chondrite, has been shown to contain abundant amounts of the three-ring PAHs phenanthrene/anthracene, but no detectable levels of the two- and four-ring PAHs naphthalene and pyrene/fluoranthene. Ivuna and other C1 carbonaceous chondrites are known to have been extensively altered by water. The aqueous solubilities of PAHs indicate that some PAHs would have been mobilized during the aqueous alteration phase in meteorite parent bodies. Model geochromatography experiments using crushed serpentine or beach sand as the solid phase and water for elution suggest that the complete separation of two, three, and four-ring PAHs could be expected to occur in the parent body of C1 carbonaceous chondrites. It is proposed that aqueous fluids driven by heat in the parent body of Ivuna migrated from the interior to the surface, in the process transporting, separating and concentrating PAHs at various zones in the parent body. The presence of indigenous PAHs and absence of indigenous amino acids in the H4 ordinary chondrite Forest Vale provides support for the contention that different processes and environments contributed to the synthesis of the organic matter in the solar system.

Parker, ET, Cleaves HJ, Dworkin JP, Glavin DP, Callahan M, Aubrey A, Lazcano A, Bada JL.  2011.  Primordial synthesis of amines and amino acids in a 1958 Miller H2S-rich spark discharge experiment. Proceedings of the National Academy of Sciences of the United States of America. 108:5526-5531.   10.1073/pnas.1019191108   AbstractWebsite

Archived samples from a previously unreported 1958 Stanley Miller electric discharge experiment containing hydrogen sulfide (H2S) were recently discovered and analyzed using high-performance liquid chromatography and time-of-flight mass spectrometry. We report here the detection and quantification of primary amine-containing compounds in the original sample residues, which were produced via spark discharge using a gaseous mixture of H2S, CH4, NH3, and CO2. A total of 23 amino acids and 4 amines, including 7 organosulfur compounds, were detected in these samples. The major amino acids with chiral centers are racemic within the accuracy of the measurements, indicating that they are not contaminants introduced during sample storage. This experiment marks the first synthesis of sulfur amino acids from spark discharge experiments designed to imitate primordial environments. The relative yield of some amino acids, in particular the isomers of aminobutyric acid, are the highest ever found in a spark discharge experiment. The simulated primordial conditions used by Miller may serve as a model for early volcanic plume chemistry and provide insight to the possible roles such plumes may have played in abiotic organic synthesis. Additionally, the overall abundances of the synthesized amino acids in the presence of H2S are very similar to the abundances found in some carbonaceous meteorites, suggesting that H2S may have played an important role in prebiotic reactions in early solar system environments.

Brinton, KLF, Bada JL.  1996.  A reexamination of amino acids in lunar soils: Implications for the survival of exogenous organic material during impact delivery. Geochimica Et Cosmochimica Acta. 60:349-354.   10.1016/0016-7037(95)00404-1   AbstractWebsite

Using a sensitive high performance liquid chromatography technique, we have analyzed both the hot water extract and the acid hydrolyzed hot water extract of lunar soil collected during the Apollo 17 mission. Both free amino acids and those derived from acid labile precursors are present at a level of roughly 15 ppb. Based on the D/L amino acid ratios, the free alanine and aspartic acid observed in the hot water extract can be entirely attributed to terrestrial biogenic contamination. However, in the acid labile fraction, precursors which yield amino acids are apparently present in the lunar soil. The amino acid distribution suggests that the precursor is probably solar wind implanted HCN. We have evaluated our results with regard to the meteoritic input of intact organic compounds to the moon based on an upper limit of less than or equal to 0.3 ppb for alpha-aminoisobutyric acid, a non-protein amino acid which does not generally occur in terrestrial organisms and which is not a major amino acid produced from HCN, but which is a predominant amino acid in many carbonaceous chondrites. We find that the survival of exogenous organic compounds during lunar impact is less than or equal to 0.8%. This result represents an example of minimum organic impact survivability. This is an important first step toward a better understanding of similar processes on Earth and on Mars, and their possible contribution to the budget of prebiotic organic compounds on the primitive Earth.

McDonald, GD, Bada JL.  1995.  A Search for Endogenous Amino-Acids in the Martian Meteorite Eeta79001. Geochimica Et Cosmochimica Acta. 59:1179-1184.   10.1016/0016-7037(95)00033-v   AbstractWebsite

The Antarctic shergottite EETA 79001 is believed to be an impact-ejected fragment of the planet Mars. Samples of the carbonate (white druse) and the basaltic (lithology A) components from this meteorite have been found to contain amino acids at a level of approximately 1 ppm and 0.4 ppm, respectively. The detected amino acids consist almost exclusively of the L-enantiomers of the amino acids commonly found in proteins, and are thus terrestrial contaminants. There is no indication of the presence of alpha-aminoisobutyric acid, one of the most abundant amino acids in several carbonaceous chondrites. The relative abundances of amino acids in the druse material resemble those in Antarctic ice, suggesting that the source of the amino acids may be ice meltwater. The level of amino acids in EETA79001 druse is not by itself sufficient to account for the 600-700 ppm of volatile C reported in druse samples and suggested to be from endogenous martian organic material. However, estimates of total terrestrial organic C present in the druse material based on our amino acid analyses and the organic C content of polar ice can account for most of the reported putative organic C in EETA 79001 druse.