Evidence for Proteogenic Peptide-like Sequences in Meteorites Through an Enzyme-Catalysed Stereoselective Hydrolysis Strategy

In this manuscript, we evidenced for the first time proteogenic like peptide sequences in meteorite thanks to an original stereoselective enzymatic hydrolysis. Within this framework, we have first characterised the amino acids content of two meteorites, Murchison and Allende, after the standard acid hydrolysis protocol currently used in astronomical studies. To reach this goal, we have developed a highly sensitive chiral LC-MS method and we have highlighted new l- and d-enantiomers, never detected before in both meteorites. These primary findings extend the list of amino acids already found in meteorites. We next investigated the presence of proteogenic like peptide sequences. For that, we have compared the amounts of amino acids l- and d-enantiomers released from either the standard acid hydrolysis or our stereoselective peptidase hydrolysis. Thanks to this strategy, we have highlighted the presence of peptide sequences involving proteogenic l-amino acids in the Murchison together with their absence in Allende, which is consistent with the respective organic content of both meteorites. Furthermore, we demonstrated that the peptide sequences were indigenous to the Murchison meteorite.