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Enantiomeric excesses in meteoritic amino acidsGas chromatographic-mass spectral analyses of the four stereoisomers of 2-amino-2,3-dimethylpentanoic acid (dl-alpha-methylisoleucine and dl-alpha-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 alpha-methyl amino acids, isovaline and alpha-methylnorvaline, although the alpha hydrogen analogs of these amino acids, alpha-amino-n-butyric acid and norvaline, were found to be racemates. With the exception of alpha-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.
Document ID
20040173025
Document Type
Reprint (Version printed in journal)
Authors
Cronin, J. R. (Arizona State University Tempe, AZ 85287-1604, United States)
Pizzarello, S.
Date Acquired
August 22, 2013
Publication Date
February 14, 1997
Publication Information
Publication: Science
Volume: 275
Issue: 5302
ISSN: 0036-8075
Subject Category
Exobiology
Distribution Limits
Public
Copyright
Other
Keywords
NASA Program Exobiology
NASA Discipline Number 52-10
Non-NASA Center
NASA Discipline Exobiology