Combined use of the potential shift correction and the simultaneous treatment of spectroscopic and electrochemical data by multivariate curve resolution: analysis of a Pb(ii)–phytochelatin system

Abstract

The combined use of differential pulse polarography (DPP), circular dichroism (CD) and multivariate curve resolution by alternating least squares (MCR-ALS), with potential shift correction for data analysis, provides valuable information on the complexation of Pb(ii) by the phytochelatin (gamma-Glu-Cys)(3)-Gly (PC(3)). All data confirm the formation of the predominant 1 : 1 Pb-PC(3) complex. However, in the presence of an excess of Pb(ii), the same complex seems to be present but with some modification in its structure. This is suggested by the shift towards more negative potentials of the DPP signal, and by a dramatic change in CD spectra. This evolution seems to be more related to a conformational change of the complex than with a modification of the electrochemical process kinetics.

Complexation of Hg2+ with α‐Lipoic and Dihydrolipoic Acids: Study by Differential Pulse Voltammetry on Rotating Au‐Disk Electrode and ESI‐MS

“…Moreover, great affinity of Hg 2þ for thiols ensures the primary formation of Hg-thiol complexes followed by their adsorption on Au electrode [13,14]. DPV data is analyzed, when possible, by MCR-ALS that has proven to be very powerful in prior studies involving phytochelatins (PC n ) [9,15], a-and bmetallothionein domains [16] and a variety of systems [11]. ) with its subsequent reduction to Hg 0 [17].…”

A novel differential pulse voltammetric method on rotating Au-disk electrode for the study of Hg2+ binding

“…Electrochemical methods can provide detailed information on processes taking place in solution because complexation or exchanging interactions can be studied gradually changing the concentration of one component with respect to another. For many systems high quality data were obtained by Differential Pulse Polarography (DPP) and analyzed by multivariate curve resolution by alternating least squares (MCR-ALS) [7][8][9]. From its first application to electrochemical data [10], MCR-ALS has demonstrated to allow one not only to determine the number of components present in certain solution equilibria, but also to understand their evolution throughout the experiment.…”

“…From its first application to electrochemical data [10], MCR-ALS has demonstrated to allow one not only to determine the number of components present in certain solution equilibria, but also to understand their evolution throughout the experiment. A great variety of systems have been investigated by different electroanalytical techniques and MCR-ALS [7][8][9][10][11][12][13][14][15][16].…”

Binding of Hg2+ by Cys, Cys-Gly and reduced glutathione: Study by differential pulse voltammetry on rotating Au-disk electrode, electrospray ionization mass-spectrometry and isothermal titration calorimetry

“…Voltammetric techniques, especially in differential pulse mode (DPP or DPV), have been widely used to study heavy metal complexes of thiol-containing peptides [9][10][11][12][13]. Here the model study of Hg 2+ complexation with Cys, Cys-Gly and GSH is carried out by the recently proposed DPV method on the rotating Au-disk electrode (Au-RDE) [14], assisted by Multivariate Curve Resolution with Alternating Least Squares (MCR-ALS).…”