[Abiogenic synthesis of peptide-like substances induced by UV-irradiation and heat].

Dry mixtures of glycine and succinic acid as well as of glycine, phenylalanine and succinic acid were exposed to UV-irradiation and heating up to 170 degrees in atmospheres of O2 and N2. Under these conditions, synthesis of substances with peptide bonds was observed. Irradiation or heating of the first mixture results in synthesis of a substance which is water soluble and capable of dialysis, exhibiting therefore low degree of polymerization. This substance contains COOH-groups, but lacks free NH2-groups. The latter reveal themselves during hydrolysis which brings about the appearance of the initial compounds. In the second mixture, which contains an aromatic amino acid, several products are synthesized some of them being presented by the insoluble and non-dialysed precipitate (polymer). Among soluble products, peptide-like substances (without free NH2-groups) and dipeptides were found. UV-irradiation causes photolysis of phenylalanine which is mixed with succinic acid; as the result, tyrosine, alanine and asparagic acid are found among the products synthesized. These amino acids are not formed during heat-induced synthesis. Abiogenic synthesis takes place more readily in the presence of O2 than in a N2 atmosphere. Irradiation of aqueous solution of the product synthesized resulted in the photolysis of the latter. The results obtained indicate that during abiogenic period, synthesis of peptides and peptide-like substances from dry mixtures of amino acids and organic acids induced by UV-irradiation and heat might take place on the litosphere.