COORDINATION OF COPPER(II) IONS BY PROLYL-ALPHA,BETA-DEHYDROAMINO ACIDS - COMPARATIVE-STUDIES AND GENERAL-CONSIDERATIONS

Potentiometric and spectroscopic measurements and theoretical calculat ions have revealed that alpha,beta-dehydroamino acid residues have a c onsiderable effect on the co-ordination ability of an adjacent amide n itrogen towards Cu2+ ions. Also the side chain of such residues affect s the stability constants and, in some cases, the binding mode of shor t peptides containing alpha,beta-dehydroamino acid residues. The theor etical calculations showed that all dehydroamino acids except alpha,be ta-dehydroalanine tend to bend a peptide chain towards a turn conforma tion. This has a very strong impact on the co-ordination ability of a dehydropeptide ligand.