Salt-induced peptide formation from amino acids in the presence of clays and related catalysts

Abstract

The salt-induced peptide formation (SIPF) reaction, starting from the amino acids glycine and/or alanine has been performed as wetting/drying cycles in the presence of the clay minerals montmorillonite and hectorite and the related catalysts alumina and silica, in order to see whether SIPF and clay-catalysed peptide synthesis reactions could have occurred simultaneously under primitive earth conditions. The results show that this is highly possible, and that peptides are formed from pure amino acids and from their mixtures as well. Montmorillonite enhances the synthesis of tripeptides and stabilises the products against hydrolysis, whereas hectorite reduces the yields of all products. The comparison with silica and alumina indicates that the silica groups should be mainly responsible for the catalytic and stabilising effects of clay minerals.