Fragment of the Murchison meteorite (at right) and isolated individual particles (shown in the test tube).

The Murchison meteorite is named after Murchison, Victoria in Australia. Fragments of the meteorite fell near the village on 28 September 1969. The meteorite, a type II carbonaceous chondrite, was found to contain common amino acids such as glycine, alanine and glutamic acid but also unusual ones like isovaline and pseudoleucine ^[1]. The initial report stated that the amino acids were racemic supporting a theory that the source is extraterrestrial. A complex mixture of alkanes was isolated as well which was similar to that found in the Miller-Urey experiment. Serine and threonine are usually considered earthly contaminants and these compounds were conspicuously absent in the samples. Image File history File links Download high resolution version (1200x800, 425 KB) Cite: Argonne National Laboratory, Department of Energy URL: http://www. ... Image File history File links Download high resolution version (1200x800, 425 KB) Cite: Argonne National Laboratory, Department of Energy URL: http://www. ... Murchison is a small rural village located on the Goulburn River in Victoria, Australia. ... A meteorite is a small extraterrestrial body that impacts the Earths surface. ... September 28 is the 271st day of the year in the Gregorian calendar (272nd in leap years). ... 1969 (MCMLXIX) was a common year starting on Wednesday (the link is to a full 1969 calendar). ... This article belongs in one or more categories. ... Chondrites are meteorites of the stony type, that have not been modified due to melting or differentiation of the parent body. ... In chemistry, an amino acid is any molecule that contains both amino and carboxylic acid functional groups. ... Glycine (Gly, G) is a nonpolar amino acid. ... Alanine is one of the 20 most common natural amino acids. ... Glutamic acid (Glu) or glutamate (the anionic form) is one of the 20 standard amino acids used by all organisms in their proteins. ... In chemistry, a racemate is a mixture of equal amounts of left- and right-handed stereoisomers of a chiral molecule. ... Extraterrestrial, as an adjective, refers to something that originates, occurs, or is located outside Earth or its atmosphere. ... It has been suggested that List of alkanes be merged into this article or section. ... The Miller-Urey experiment attempts to recreate the chemical conditions of the primitive Earth in the laboratory, and synthesized some of the building blocks of life. ... Serine is one of the 20 natural amino acids. ... Threonine is one of the 20 natural amino acids. ...

More research found that some amino acids were present in enantiomeric excess ^[2]. Homochirality is considered a unique biological property. The claims were challenged on the grounds that the protein amino acids were non-racemic but the other amino acids were ^[3]. In 1997 research showed that individual amino-acid enantiomers from Murchison were enriched in the nitrogen isotope ¹⁵N relative to their terrestrial counterparts, which confirmed an extraterrestrial source for an L-enantiomer excess in the Solar System ^[4]. The list of organic materials identified on the meteority material was extented to polyols ^[6] by 2001. In chemistry two stereoisomers are said to be enantiomers if one can be superimposed on the mirror image of the other. ... In chemistry, a molecule is chiral if it is not superimposable on its mirror image regardless of how it is contorted. ... In chemistry two stereoisomers are said to be enantiomers if one can be superimposed on the mirror image of the other, and vice versa. ... Isotopes are forms of an element whose nuclei have the same atomic number - the number of protons in the nucleus - but different mass numbers because they contain different numbers of neutrons. ... A sugar alcohol (also known as a polyol, polyhydric alcohol, or polyalcohol) is a hydrogenated form of carbohydrate, whose carbonyl group (aldehyde or ketone, reducing sugar) has been reduced to a primary or secondary hydroxyl group. ...

Pair of grains from the Murchison meteorite.

Building on the idea that homochirality (existence of only left handed amino acids and right handed sugars) is triggered by deposition of chiral molecules on meteorites, research in 2005 demonstrated that an amino acid like L-proline is capable of catalyzing the formation of chiral sugars. The catalysis is non-linear, that is proline with an enantiomeric excess of 20% yields a allose with enantiomeric excess of 55% starting from a benzyloxy acetaldehyde in a sequential aldol type reaction in an organic solvent like DMF ^[5]. In other words a small amount of chiral amino acids may explain the evolution of right-handedness of sugars. Image File history File links Murchison-meteorite-stardust. ... Image File history File links Murchison-meteorite-stardust. ... L-Proline is one of the twenty proteinogenic units which are used in living organisms as the building blocks of proteins. ... Generic graph showing the effect of a catalyst in an hypotetical exothermic chemical reaction. ... In chemistry two stereoisomers are said to be enantiomers if one can be superimposed on the mirror image of the other. ... Allose is an aldohexose sugar. ... An aldol reaction takes the following form: 2 enolate anions ↔ aldol The reaction requires a base catalyst. ... Dimethylformamide, also known under the names N,N-dimethylformamide and DMF, is a clear, water-miscible liquid and common solvent that is often used in chemical reactions. ...

References

• ^[1] Evidence for extraterrestrial amino-acids and hydrocarbons in the Murchison meteorite Keith Kvenvolden K, Lawless J, Pering K, Peterson E, Flores J, Ponnamperuma C, Kaplan IR, Moore C. Nature 923 228 1970 abstract
• ^[2] Distribution and enantiomeric composition of amino acids in the Murchison meteorite Michael H. Engel and Bartholomew Nagy, Nature 837 296 1982. abstract
• ^[3] On the reported optical activity of amino acids in the Murchison meteorite Jeffrey L. Bada, John R. Cronin, Ming-Shan Ho, Keith A. Kvenvolden, James G. Lawless, Stanley L. Miller, J. Oro & Spencer Steinberg Nature 494 301 1983 abstract
• ^[4] Isotopic evidence for extraterrestrial non- racemic amino acids in the Murchison meteorite M. H. Engel AND S. A. Macko. Nature 265 389 1997. abstract
• ^[5] Plausible origins of homochirality in the amino acid catalyzed neogenesis of carbohydrates Armando Córdova , Magnus Engqvist , Ismail Ibrahem , Jesús Casas, Henrik Sundén Chem. Commun., 2005, (15), 2047 - 2049 [1]
• ^[6] Carbonaceous meteorites as a source of sugar-related organic compounds for the early Earth George Cooper, Novelle Kimmich, Warren Belisle, Josh Sarinana, Katrina Brabham, Laurence Garrel Nature 879 414 2001 abstract