Amino acid signatures in carbonaceous meteorites

Abstract

Carbonaceous chondrites, a class of stony meteorites that contains up to 3 weight-% of organic carbon, are subdivided into types by chemical and mineralogical characteristics. These meteorites are thought to originate from asteroidal parent bodies on which secondary processing in the early history of the solar system has altered interstellar organic precursors into more complex compounds such as amino acids and nucleobases. We have analyzed nine different carbonaceous chondrites and have compared the total and relative amino acid concentrations of hydrolyzed hot-water extracts of these meteorites. When the relative amino acid concentrations [(Beta) -alanine]/[glycine], [AIB]/[glycine] and [D- alanine]/[glycine] of meteorites are plotted against each other, a clustering of the data points of the CM and CI type carbonaceous chondrites can be observed. This signature indicates that the amino acids in the Cms were synthesized via the Strecker synthetic pathway, whereas the amino acids found in the Cis probably have a different synthetic origin.