Isotopic evidence for extraterrestrial non- racemic amino acids in the Murchison meteorite

  title={Isotopic evidence for extraterrestrial non- racemic amino acids in the Murchison meteorite},
  author={Michael H. Engel and Stephen A. Macko},
Many amino acids contain an asymmetric centre, occurring as laevorotatory, L, or dextrorotatory, D, compounds. It is generally assumed that abiotic synthesis of amino acids on the early Earth resulted in racemic mixtures (L- and D-enantiomers in equal abundance). But the origin of life required, owing to conformational constraints, the almost exclusive selection of either L- or D-enantiomers, and the question of why living systems on the Earth consist of L-enantiomers rather than D-enantiomers… Expand
The stereochemistry of amino acids in the Murchison meteorite
Abstract The questions of how, where and when life originated in our solar system remain largely unanswered. Some advances have been made with respect to abiotic synthesis of the key molecules deemedExpand
Racemization of Meteoritic Amino Acids
Abstract Meteorites may have contributed amino acids to the prebiotic Earth, affecting the global ratio of right-handed to left-handed (D/L) molecules. We calculate D/L ratios for seven biological,Expand
Pathways for the asymmetric amplification of protein amino acids in the Murchison meteorite
The amplification of L-enantiomers of amino acids from racemates was likely a precondition for the origin of life on Earth. Engel and Nagy1 first reported that seven protein amino acids in theExpand
Possible effects of diagenesis on the stable isotope composition of amino acids in carbonaceous meteorites
  • M. Engel
  • Chemistry, Engineering
  • SPIE Optical Engineering + Applications
  • 2015
The initial report of indigenous, non-racemic protein amino acids (L-enantiomer excess) in the Murchison meteorite was based on the fact that only eight of the twenty amino acids characteristic ofExpand
Nonracemic isovaline in the Murchison meteorite : Chiral distribution and mineral association
Abstract The enantiomeric and carbon-isotopic composition of the amino acid isovaline have been analyzed in several samples of the Murchison meteorite and one sample of the Murray meteorite. lExpand
Unusual Nonterrestrial L-proteinogenic Amino Acid excesses in the Tagish Lake Meteorite
The distribution and isotopic and enantiomeric compositions of amino acids found in three distinct fragments of the Tagish Lake C2-type carbonaceous chondrite were investigated via liquidExpand
Molecular and chiral analyses of some protein amino acid derivatives in the Murchison and Murray meteorites
— The varied organic suite extracted from the Murchison meteorite contains several amino acids that are common to the biosphere. Some of these have been found to be non-racemic, but the indigenousExpand
The deuterium enrichment of individual amino acids in carbonaceous meteorites: A case for the presolar distribution of biomolecule precursors
The δD values of over 40 amino acids and two pyridine carboxylic acids of the Murchison and Murray meteorites have been obtained by compound-specific isotopic analyses. For compounds with no knownExpand
Amino Acid Enantiomer Excesses in Meteorites: Origin and Significance
Abstract The presence of small l -excesses in both of the two enantiomeric pairs of 2-amino-2,3-dimethylpentanoic acid, in 2-amino-2-methylbutanoic acid (Isovaline), and in 2-amino-2-methylpentanoicExpand
Assessing the origins of aliphatic amines in the Murchison meteorite from their compound-specific carbon isotopic ratios and enantiomeric composition
The study of meteoritic organic compounds provides a unique window into the chemical inventory of the early Solar System and prebiotic chemistry that may have been important for the origin of life onExpand


Carbon isotope composition of individual amino acids in the Murchison meteorite
The amino acids in the Murchison meteorite are enriched in 13C, indicating an extraterrestrial origin, and Alanine is not racemic, and the 13C enrichment of its D- and L-enantiomers implies that the excess of the L- enantiomer is indigenous rather than terrestrial contamination, suggesting that optically active materials were present in the early Solar System before life began. Expand
Distribution and enantiomeric composition of amino acids in the Murchison meteorite
Early determinations of the amino acid distribution in water extracts of the Murchison meteorite revealed unusual amino acids, including isovaline (Ival), α-aminoisobutyric acid (α-Aiba) andExpand
Unusual stable isotope ratios in amino acid and carboxylic acid extracts from the Murchison meteorite
The isotopic composition of hydrogen, nitrogen and carbon in amino acid and monocarboxylic acid extracts from the Murchison meteorite confirms the extraterrestrial origin of both classes of compound, and provides the first evidence suggesting a direct relationship between the massive organo-synthesis occurring in interstellar clouds and the presence of pre-biotic compounds in primitive planetary bodies. Expand
Isotopic analyses of amino acids from the Murchison meteorite.
The results indicate that the Murchison amino acids are truly isotopically unusual, that the isotopic excesses reside in at least several different amino acids, and thatThe isotopic contents of some of these amino acids reach values of about +40% (delta 13C) and +2500% ( delta D). Expand
Enantiomeric Excesses in Meteoritic Amino Acids
Gas chromatographic-mass spectral analyses of the four stereoisomers of 2-amino-2,3-dimethylpentanoic acid obtained from the Murchison meteorite show that the L enantiomer occurs in excess, indicative of an asymmetric influence on organic chemical evolution before the origin of life. Expand
Organic matter in meteorites: molecular and isotopic analyses of the Murchison meteorite.
Carbonaceous chondrites comprise a unique subset of meteorites. Two classes of carbonaceous chondrites, the so-called CI1 and CM2 chondrites, are particularly interesting, in part because of theirExpand
Carbon isotope composition of low molecular weight hydrocarbons and monocarboxylic acids from Murchison meteorite
The results suggest the possibility that the production mechanisms for hydrocarbons and carboxylic acids may be similar and impose constraints on the identity of the reactant species, and are consistent with the kinetically controlled synthesis of higher homologues from lower ones. Expand
The Organic Geochemistry of Carbonaceous Meteorites
The stable carbon isotope record of bulk organic matter (i.e., kerogen) in ancient rock samples indicates that living systems may have existed on Earth 3.5 billion years ago (e.g., Schidlowski,Expand
Isotopic analyses of nitrogenous compounds from the Murchison meteorite: ammonia, amines, amino acids, and polar hydrocarbons.
The delta 15N values of the Murchison soluble organic compounds analyzed to date fall within a rather narrow range, an observation consistent with their formation, or formation of their precursors, by interstellar chemistry. Expand
Summary and implications of reported amino acid concentrations in the Murchison meteorite
The possibility of sampling bias needs to be tested experimentally before concluding that extraction is complete, and that the constant relative abundances indicate that the relative concentrations of amino acids are homogeneous in the meteorite. Expand