The Catalytic Activity of Water Clusters Towards Peptide Bond Formation as a Model for the Prebiotic Origins of Oligopeptides: A Spontaneous First Step Towards Life

The emergence of life in the prebiotic Earth must have involved the formation of polypeptides, yet the polymerization of amino acids is thermodynamically unfavorable under biologically relevant conditions due to the production of a water molecule via condensation. We hypothesize that atmospheric aerosols catalyzed the prebiotic formation of peptide bonds to form oligopeptides by providing the correct molecular orientations to start the condensation reaction. We have tested this hypothesis using density-functional theory combined with an extensive sampling scheme to sample configurational space. The dimerization and trimerization of glycine through condensation are spontaneous in the gas phase and increase in spontaneity as one to three catalytic water molecules are added. This increase is driven by the stability of the product clusters which can bend to maximize the intra- and intermolecular binding interactions, specifically hydrogen bonding