Peptide synthesis triggered by comet impacts: A possible method for peptide delivery to the early Earth and icy satellites

Synthesis of functionalized nitrogen-containing polycyclic aromatic hydrocarbons and other prebiotic compounds in impacting glycine solutions

“…A longer ve backbone carbon chain was also iden-tied, reminiscent of the oligomers produced in shock experiments performed on glycine and alanine. 25,27 Several different recovered species are known metabolic products or intermediates, including guanidine, urea, and carbamic acid. We also note that guanidine is an important structural component in the proteinogenic amino acid arginine.…”

“…Moieties reminiscent of amino acids with neighboring amine and carboxyl groups were also found along the periphery of NPAHs. It is highly likely that chemical reactivity in these systems would be enhanced by the presence of catalytic surfaces such as as silicates, 25,27 which is the subject of future work.…”

“…18,19 Recent experimental observations 20,21 conrming the presence of the protein-forming amino acid glycine in comets lend support to cometary impact as a possible source for delivering simple amino acids to ancient Earth. 18,19,[21][22][23][24][25][26][27] Laboratory experiments and theoretical studies show that impacting simple chemical mixtures can form more complicated nitrogencontaining species, including small heterocycles and amino acids. 18,19,24,26 The possibilities for impact-initiated chemistry starting from more complicated precursors such as glycine are perhaps even more diverse.…”

“…29 Shocking frozen mixtures of simple amino acids such as glycine or alanine in the presence of a silicate was shown to facilitate condensation into short peptide chains in a laboratory model for cometary impact. 25,27 Although oligomers up to the trimer were observed, a mass census of reactant and product concentrations revealed that most of the precursor molecules decomposed into other unidentied products for strong shocks (P > 25 GPa).…”

Mechanochemical synthesis of glycine oligomers in a virtual rotational diamond anvil cell

“…Blank et al performed shock experiments on an aqueous solution of amino acids in the pressure range of 5.1-21 GPa and temperature range of 412-870 K and observed the formation of polypeptides up to dimers. 16 More recently, Sugahara and Mimura performed shock experiments up to 26.3 GPa on cryogenic (77 K) model cometary icy mixtures containing glycine 22 and alanine 37 and showed oligomerization up to trimers. Sugahara and Mimura also found yields of glycylglycine (diglycine) of up to 1.5% mol ratio of products to reactants and that the yield roughly increases with shock pressure.…”