Impact of α-hydroxymethylserine (HmS) residue on the binding ability of the histidyl residue in the HmS-His dipeptide towards CuII, NiII and ZnII

Abstract

Potentiometric and spectroscopic data have shown that α-hydroxymethylserylhistidine is a very efficient ligand for Cu^II, Ni^II and Zn^II. The stabilities of the complexes formed are considerably higher than those obtained for Gly-His or Ala-His dipeptides. Copper(II) and Ni^II form very stable tetrameric complexes M₄H_–8L₄. According to ¹H NMR spectra the nickel tetrameric complex is of C₂ symmetry with two pairs of different imidazole rings. Zinc(II), on the other hand, forms only monomeric species but due to the second His residue it forms very stable ZnH_–1L species via a {NH₂,N^–_amide,N_imidazole} donor set.