Zinc-binding properties of the C-terminal hexapeptide Lys–Cys–Thr–Cys–Cys–Ala from mouse metallothionein: analysis by differential pulse polarography and multivariate curve resolution Original Research Article

The zinc-binding properties of the C-terminal hexapeptide of mouse metallothionein I, Lys–Cys–Thr–Cys–Cys–Ala, were studied by differential pulse polarography (DPP) with a recently proposed multivariate curve resolution (MCR) method, based on factor analysis techniques, which allows the identification of the signal corresponding to different metal ions bound in different chemical environments. From DPP results obtained at different Zn2+-to-peptide concentration ratios and at different pH values, the formation of different Zn2+–peptide complexes is deduced, and a scheme for the electrochemical reduction of the complexed Zn2+ ions is proposed. Two complexes have been detected: the first one is formed at low Zn-to-FT concentration ratios and shows a 1:2 Zn:FT stoichiometry; at higher ratios a second Zn2+ is incorporated yielding a Zn2FT2 complex which probably contains a binuclear cluster.