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

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 mixed-metal complexes, with higher stoichiometries than those of the binary Cd-peptide and Zn-peptide 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. (C) 2001 Elsevier Science B.V. All rights reserved.