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 CuII, NiII and ZnII. The stabilities of the complexes formed are considerably higher than those obtained for Gly-His or Ala-His dipeptides. Copper(II) and NiII 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,Nimidazole} donor set.