Copper(II) and zinc(II) complexes of glycylglycyl-L-histidine and derivatives

Abstract

Computer-assisted analysis of pH-titration data has afforded equilibrium constants at 37 °C and /= 0.15 mol dm^–3. (K[NO₃]) for copper(II) and zinc(II) complexes of glycylglycyl-L-histidine (Gly-Gly-His), Gly-Gly-His-Gly-Gly, their alkyl esters, and their benzyloxycarbonyl derivatives. The types of complexes and their equilibrium values are similar to those formed by Gly-His. Binuclear complexes are major components of the systems containing Zn^II. The copper peptide complexes are reasonable models for the binding of Cu^II by albumin, but the disparity between constants for zinc–peptide and –albumin complexes indicates that a different binding site is involved.