Extraterrestrial amino acids in Orgueil and Ivuna: Tracing the parent body of CI type carbonaceous chondrites

^*Raymond and Beverly Sackler Laboratory for Astrophysics at Leiden Observatory, P.O. Box 9513, 2300 RA, Leiden, The Netherlands; ^‡Scripps Institution of Oceanography, University of California at San Diego, La Jolla, CA 92093-0212B; and ^§National Aeronautics and Space Administration AMES Research Center, Exobiology Branch, P.O. Box 204, Moffett Field, CA 94035

Edited by Donald E. Brownlee, University of Washington, Seattle, WA, and approved December 29, 2000 (received for review October 23, 2000)

Abstract

Amino acid analyses using HPLC of pristine interior pieces of the CI carbonaceous chondrites Orgueil and Ivuna have found that β-alanine, glycine, and γ-amino-n-butyric acid (ABA) are the most abundant amino acids in these two meteorites, with concentrations ranging from ≈600 to 2,000 parts per billion (ppb). Other α-amino acids such as alanine, α-ABA, α-aminoisobutyric acid (AIB), and isovaline are present only in trace amounts (<200 ppb). Carbon isotopic measurements of β-alanine and glycine and the presence of racemic (D/L ≈ 1) alanine and β-ABA in Orgueil suggest that these amino acids are extraterrestrial in origin. In comparison to the CM carbonaceous chondrites Murchison and Murray, the amino acid composition of the CIs is strikingly distinct, suggesting that these meteorites came from a different type of parent body, possibly an extinct comet, than did the CM carbonaceous chondrites.

Footnotes

↵ † To whom reprint requests should be addressed. E-mail: pascale{at}strw.leidenuniv.nl or jbada{at}ucsd.edu.
This paper was submitted directly (Track II) to the PNAS office.
Abbreviations:

AIB,

aminoisobutyric acid;

ppb,

parts per billion;

ABA,

amino-n-butyric acid;

HCN,

hydrogen cyanide