Cyanamide mediated syntheses under plausible primitive earth conditions. III. Synthesis of peptides

Peptides were formed in yields of 5%, 17% and 66%, respectively, when aqueous solutions of glycine, isoleucine or phenylalanine were dried and heated for 24 h at 90 degrees C with adenosine 5'-triphosphate, 4-amino-5-imidazolecarboxamide and cyanamide. Glycine and L-phenylalanine produced mixtures of di-, tri- and tetrapeptides, while L-isoleucine gave only the dipeptide in detectable quantities. The dipeptides of L-isoleucine and L-phenylalanine were identified by mass spectrometry and enzymatic and enzymatic degradation.