Impact of alpha,beta-dehydroamino acid residues on the binding abilities of di-, tri- and tetra-peptides

Insertion of a dehydroamino acid residue into a sequence of di-, tri- or te tra-peptide changed considerably the binding abilities of peptide ligands t owards copper(II) ions. Potentiometric and spectroscopic (EPR, UV-VIS and C D) data have shown that the amide nitrogen of the dehydroamino acid residue is more effective in co-ordination than its parent analogue. In the case o f the bulky Delta Phe residue also the (Z-E) isomerisation has a critical i mpact on the co-ordination equilibria in the system studied.