Racemization of Meteoritic Amino Acids


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, α-hydrogen, protein amino acids over a variety of plausible parent body thermal histories, based on meteorite evidence and asteroid modeling. We show that amino acids in meteorites do not necessarily undergo complete racemization by the time they are recovered on Earth. If the mechanism of amino acid formation imposes some enantiomeric preference on the amino acids, a chiral signature can be retained through the entire history of the meteorite. Original enantiomeric excesses in meteorites such as Murchison, which have undergone apparently short and cool alteration scenarios, should have persisted to the present time. Of the seven amino acids for which relevant data are available, we expect glutamic acid, isoleucine, and valine, respectively, to be the most likely to retain an initial enantiomeric excess, and phenylalanine, aspartic acid, and alanine the least. Were the D/ L ratio initially identical in each amino acid, final D/ L ratios could be used to constrain the initial ratio and the thermal history experienced by the whole suite. c © 2000 Academic Press

7 Figures and Tables


Citations per Year

104 Citations

Semantic Scholar estimates that this publication has 104 citations based on the available data.

See our FAQ for additional information.

Cite this paper

@inproceedings{Cohen2000RacemizationOM, title={Racemization of Meteoritic Amino Acids}, author={Barbara A. Cohen and Christopher Chyba}, year={2000} }