PEPTIDE-CHAIN ELONGATION - A POSSIBLE ROLE OF MONTMORILLONITE IN PREBIOTIC SYNTHESIS OF PROTEIN PRECURSORS

Several studies have proven the ability of montmorillonite to catalyst amino acid condensation under assumed prebiotic conditions, simulatin g wetting-drying cycles. In this work, the oligomerization of short pe ptides gly(2), gly(3), gly(4) and ala(2) on Ca- and Cu-montmorillonite in drying-wetting cycles at 80 degrees C was studied. The catalytic e ffect of montmorillonite was found to be much higher than in the case of glycine oligomerization. From gly(2) after 3 weeks, 10% oligomers ( up to gly(6), with gly(3) as main products) are formed. Gly(3) and gly (4) give higher oligomers even after 1 cycle. Ala(2) produces both ala (3) and ala(4), whereas ala does not produce any oligomers under these conditions. Heteroologomerization was observed: ala-gly-gly is formed from ala and gly(2). Much higher yields are obtained using Ca-montmor illonite, because copper (II) oxidizes organic molecules. The influenc e of the reaction mechanism on the preferential oligomerization of oli gopeptides is discussed.