Amino-acids, Aliphatic and Aromatic Hydrocarbons in the Murchison Meteorite

Abstract

Two recently fallen carbonaceous chondrites have provided organic analytical results significantly different from those obtained with other carbonaceous chondrites^1–3. The Allende meteorite, a type III carbonaceous chondrite which contains 0.27% carbon and 0.007% nitrogen⁴, was shown to have only traces of extractable organic compounds⁵. Small amounts of aliphatic and aromatic hydrocarbons were released by heating while no significant amounts of nitrogen containing compounds were detected^6–8. This is consistent with the extremely low nitrogen content of this carbonaceous chondrite. Another unique feature of this meteorite is the heterogenous distribution of certain carbon-containing inclusions⁹. The Murchison meteorite, a type III carbonaceous chondrite, contains substantial amounts of amino-acids, predominantly cyclic aliphatic hydrocarbons¹⁰, which are consistent with the appreciable content of carbon and nitrogen of this meteorite (2 and 0.16% respectively). The amino-acids include non-protein components such as sarcosine and 2-methylalanine and, significantly, approximately racemic mixtures of D and L enantiomers of protein amino-acids such as alanine, valine and proline¹⁰.