COPPER(II) COMPLEXES OF DIPEPTIDES CONTAINING ASPARTYL, GLUTAMYL, ANDHISTIDYL RESIDUES IN THE SIDE-CHAIN

Copper(II) complexes of various dipeptides containing carboxylate and imidazole-N3 donors (alpha- and gamma-GluVal, alpha- and beta-AspGly, beta-AspHis, gamma-GluHis, and homocarnosine) were studied by potentio metric and spectroscopic methods in solution. It was found that the pr esence of an alpha-carboxylate group in the N-terminal part of a pepti de molecule significantly enhances the metal-binding ability of the li gands as a consequence of stable bis complex formation involving amino acid-like coordination. The interaction of copper(II) with beta-AspHi s was characterized by the formation of an imidazole-bridged dimeric s pecies, while the formation of bis complexes was detected in the case of gamma-GluHis. Binding of the imidazole N3 and deprotonated amide ni trogen was presumed in the copper(II)-homocarnosine system.