The carbon isotopic distribution of Murchison amino acids

The delta(13)C values of thirty-four individual amino acids and two pyridine carboxylic acids have been obtained from the Murchison meteorite. They were found to range from +4.9 to +52.8parts per thousand, with statistically significant differences observed both within and between amino acid subgroups. The C-13 content of a-amino acids declines with increasing chain length, a trend similar to the ones previously observed for carboxylic acids and alkanes. Also 2-methyl-2-amino acids were found to be heavier in C-13 than the corresponding 2-H homologues. The 3-, 4-, and 5-amino acids do not show a comparable declining trend in VC values and neither do the amino dicarboxylic acids. This Variability in delta(13)C values can be interpreted as to indicate that the synthetic histories of soluble organics in meteorites may have been diverse even within groups of compounds with very similar functional group composition. Copyright (C) 2004 Elsevier Ltd.