Extraterrestrial Hydroxy Amino Acids in CM and CR Carbonaceous Chondrites

7 The abundances, distributions, and enantiomeric ratios of a family of three- and four-
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10 carbon hydroxy amino acids (HAAs) were investigated in extracts of five CM and four
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13 CR carbonaceous chondrites by gas chromatography-mass spectrometry (GC-MS)
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16 analyses. Hydroxy amino acids were detected in both the acid hydrolysates of the hot
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19 water extracts and the 6 M HCl extracts of all the CM and CR chondrites analyzed
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22 here with total hot water and HCl extractable HAA concentrations ranging from 6.94
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25 to 315 nmol per gram. The HAA analyses performed in this study revealed: 1) the
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28 combined (hot water + HCl) extracts of CR2 chondrites contained greater abundances
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31 of -HAAs than that of CM2 chondrites and 2) the combined extracts of CM and CR
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34 chondrites contained roughly similar abundances of β- and γ-HAAs. Application of the
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37 new GC-MS method developed here resulted in the first successful chromatographic
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40 resolution of the enantiomers of an -dialkyl HAA, D,L--methylserine, in
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43 carbonaceous chondrite extracts. Meteoritic -methylserine was found to be mostly
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46 racemic within error and did not show L-enantiomeric excesses correlating with the
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49 degree of aqueous alteration, a phenomenon observed in meteoritic isovaline, another
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52 -dialkyl amino acid. The HAAs identified in CM and CR chondrite extracts could have
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55 been produced during parent body alteration from the Strecker cyanohydrin reaction
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58 (for -HAAs) and an ammonia-involved formose-like reaction (for β-, and γ-HAAs).