Zbigniew Kubica

Coordination of copper(II) ions by α,β-dehydro-dipeptides. Potentiometric and spectroscopic study

Abstract Potentiometric and spectroscopic data have shown that the double bond within dehydro-peptides considerably affects their behaviour as ligands relative to their saturated parents, with proton and copper(II) ions.

Unusual binding ability of α,β-dehydrodipeptides towards metal ions

Abstract Ni II , Zn II and Co II complexes of α,β-dehydro-dipeptides (containing Gly, Leu, Ala, Val or Phe residues) were studied by potentiometric and spectroscopic methods. Deprotonation and coordination of amide nitrogens occurred in all cases around the physiological pH range. The dipeptides with composition of Xaa-Δ-Ala formed octahedral species, while Gly-Δ-Xaa (Xaa = Leu or Phe) formed square planar bis complexes with Ni II .

Co-ordination of copper(II) ions by prolyl-α,β-dehydroamino acids: comparative studies and general considerations

Potentiometric and spectroscopic measurements and theoretical calculations have revealed that α,β-dehydroamino acid residues have a considerable effect on the co-ordination ability of an adjacent amide nitrogen towards Cu2+ ions. Also the side chain of such residues affects the stability constants and, in some cases, the binding mode of short peptides containing α,β-dehydroamino acid residues. The theoretical calculations showed that all dehydroamino acids except α,β-dehydroalanine tend to bend a peptide chain towards a turn conformation. This has a very strong impact on the co-ordination ability of a dehydropeptide ligand.