Square wave voltammetry data analysis by multivariate curve resolution: application to the mixed-metal system Cd-Zn-{Lys-Cys-Thr-Cys-CysAla}

An electrochemical study of the complexing properties of the C-terminal peptidic fragment Lys-Cys-Thr-Cys-Cys-Ala {56-61} of mouse liver MT 1 in the simultaneous presence of cadmium and zinc has been performed at pH 8.0. Even using a high resolution technique as square wave voltammetry, rather involved voltammetric signals with highly overlapping peaks were obtained. In order to reach a proper interpretation of the voltammetric data, a multivariate curve resolution with alternating least squares optimization (MCR-ALS) method has been applied. MCR-ALS allows one to obtain both the unitary voltammogram for each electrochemical process and the concentration profiles along the experiment. The formation of ternary mixedmetal complexes, with higher stoichiometries than those of the binary Cd-peptide and Znpeptide is reported. Results are compared with those obtained from previous studies but without multivariate data analysis, and with some results concerning metallothioneins and their alpha- and beta-domains.