Catalytic non-energetic formation of diverse peptides on cosmic dust under extraterrestrial conditions.

This study experimentally examines a non-energetic pathway for peptide formation under realistic space conditions. Unlike radiation-driven processes, this mechanism involves low- or zero-barrier reactions at cryogenic temperatures. This provides a less stochastic chemical pathway and favours molecular growth over fragmentation. Experiments conducted in ultra-high vacuum involve some of the most abundant cosmic species, such as H, C, CO, H2O, and NH3. The results demonstrate efficient peptide and peptide-derivative synthesis driven by the catalytic activity of organics formed during condensation. This self-enhancing chemistry suggests that peptides may act as catalysts, supporting molecular self-organization under astrophysical conditions. The addition of atomic hydrogen as a reactant increases molecular diversity, thus yielding peptides that contain glycine, alanine, serine, and threonine residues. Moreover, hydrogen substantially boosts polymerization efficiency, generating longer peptides and insoluble organic matter. These findings provide strong evidence that various peptides form in cold, extraterrestrial environments. The targeted search for non-canonical peptides H(NHCH2CO)nNH2 and H(NHCH2CO)nH, efficiently formed in our experiments, in meteorites and during space missions, may not only confirm the feasibility of this pathway of extraterrestrial chemistry but also provide new insights into the origins of life.