| Abstract: | In analyses of extracts from the Murchison meteorite (a carbonaceous chondrite), Engel and Nagy1 reported an excess of L-enantiomers for several protein amino acids but found that the non-protein amino acids were racemic. They suggested that the excess of L-isomers might have resulted from an asymmetric synthesis or decomposition. Their results disagree with those obtained previously2-4 and they claim this is due to improved methodology. In fact, their extraction method and analytical procedure (gas chromatography-mass spectrometry, GC-MS) was similar to those used in the original report2 of amino acids in the Murchison meteorite except that they used specific ion monitoring in the GC-MS measurements. We found the results of Engel and Nagy odd in that likely contaminants (the protein amino acids ala, leu, glu, asp and pro) were nonracemic while unlikely contaminants (isovaline and ??-amino-n-butyric acid) were racemic. For example, Engel and Nagy report that the leucine is ???90% L-enantiomer in the water-extracted sample whereas isovaline (??-methyl-??-aminobutyric acid) is racemic. It would be most unusual for an abiotic stereoselective decomposition or synthesis of amino acids to occur with protein amino acids but not with non-protein amino acids. We now show here that the explanation of terrestrial contamination is consistent with their results and is much more probable. ?? 1983 Nature Publishing Group. |
| Genre: | Article |
| ProdID: | 70011372 |
| Citation Author: | Bada, J. L.; Cronin, J. R.; Ho, M. -S.; Kvenvolden, K. A.; Lawless, J. G.; Miller, S. L.; Oro, J.; Steinberg, S. |
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| Citation End Page: | 496 |
| Citation Issue: | 5900 |
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| Citation Language: | English |
| Citation Larger Work Title: | Nature |
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| Citation Number Of Pages: | 3 |
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| Citation Search Results Text: | On the reported optical activity of amino acids in the Murchison meteorite; 1983; Article; Journal; Nature; Bada, J. L.; Cronin, J. R.; Ho, M. -S.; Kvenvolden, K. A.; Lawless, J. G.; Miller, S. L.; Oro, J.; Steinberg, S. |
| Citation Start Page: | 494 |
| Citation Volume: | 301 |
| Citation Year: | 1983 |
| Type: | citation/reference |
| Text: | On the reported optical activity of amino acids in the Murchison meteorite; 1983; Article; Journal; Nature; Bada, J. L.; Cronin, J. R.; Ho, M. -S.; Kvenvolden, K. A.; Lawless, J. G.; Miller, S. L.; Oro, J.; Steinberg, S. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| URL (DIGITAL OBJECT IDENTIFIER): | http://dx.doi.org/10.1038/301494a0 |
| Date Other: | Sat, 1 Jan 1983 00:00 -0600 |
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