such as "Introduction", "Conclusion"..etc
* 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)
Amino acid analyses using HPLC of pristine interior pieces of the CI carbonaceous chondrites Orgueil and Ivuna have found that -alanine, glycine, and -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 -amino acids such as alanine, -ABA, -aminoisobutyric acid (AIB), and isovaline are present only in trace amounts ( isotopic measurements of -alanine and glycine and the presence of racemic (D/L 1) alanine and -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.
PNAS February 27, 2001 vol. 98 no. 5 p 2138-2141.
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