Copper(II) complexes of low molecular weight derivatives of thymopoietin.

Copper(II) complexes of tri- and tetrapeptides containing either carboxylate or amide group in the side chain were studied by potentiometric and spectroscopic methods. The ligands are tri- and tetrapeptide segments of the hormones thymopoietin and splenin. It was found that internal aspartyl residues significantly enhance the metal binding ability of oligopeptides, resulting in the cooperative deprotonation of the amide nitrogens preceding the aspartyl residue, while the subsequent amide groups do not take part in metal ion coordination. Glutamyl residues have no significant effect on the complex formation processes of oligopeptides.