Enantiomeric Excesses in Meteoritic Amino Acids

See allHide authors and affiliations

Science  14 Feb 1997:
Vol. 275, Issue 5302, pp. 951-955
DOI: 10.1126/science.275.5302.951

You are currently viewing the abstract.

View Full Text


Gas chromatographic-mass spectral analyses of the four stereoisomers of 2-amino-2,3-dimethylpentanoic acid (DL-α-methylisoleucine and DL-α-methylalloisoleucine) obtained from the Murchison meteorite show that the L enantiomer occurs in excess (7.0 and 9.1%, respectively) in both of the enantiomeric pairs. Similar results were obtained for two other α-methyl amino acids, isovaline and α-methylnorvaline, although the α hydrogen analogs of these amino acids, α-amino-n-butyric acid and norvaline, were found to be racemates. With the exception of α-amino-n-butyric acid, these amino acids are either unknown or of limited occurrence in the biosphere. Because carbonaceous chondrites formed 4.5 billion years ago, the results are indicative of an asymmetric influence on organic chemical evolution before the origin of life.

View Full Text