Multivariate Curve Resolution of Cyclic Voltammetric Data:  Application to the Study of the Cadmium-Binding Properties of Glutathione

Abstract

Multivariate curve resolution is applied to cyclic voltammetry (CV) data obtained in the study of Cd(II) complexation by glutathione (GSH). The relatively poor resolution of CV hinders the direct interpretation of raw data. The use of CV is improved by the combination of several chemometric techniques based on factor analysis: singular-value decomposition, evolving factor analysis, and multivariate curve resolution with constrained alternating least squares optimization including a new peak-shape constraint. This multivariate analysis data treatment simultaneously reveals the formation of Cd(GSH)2 and Cd2(GSH)2 complexes, through the calculated concentration profiles, and allows the assignment of numerically obtained pure individual CV signals for the different Cd(II) ions present in solution (free and bound) and involved in the electrochemical process.

Voltammetry and EQCM Investigation of Glutathione Monolayer and Its Complexation with Cu2+

“…The SAM on mercury surface is very different from the one on gold surface, the former seems looser and can not inhibit the electron-transferring process completely [13,27]. If the complexation of Cu 2 ion with GSH monolayer has the ability to accumulate the ion of Cu 2 , as mentioned above, the redox peak of Cu 2 should enlarge in the presence of GSH SAM than in the absence, which can be confirmed from the results obtained from Figure 6.…”

“…The metal-binding properties of GSH to Cd 2 were also studied by using cyclic voltammetry and multivariate curve resolution (MCR). The formation of Cd(GSH) 2 and Cd 2 (GSH) 2 was revealed simultaneously by this kind of data treatment method [12,13]. On the other hand, the peptides and polypeptides modified electrodes based on the SAM were also reported, such as 32 ± 96 aspartate units PLAsp for sub-ppb detection for Cu 2 , Gly-Gly-His monolayer for subppt detection for Cu 2 , and so on [14,15].…”

“…The electrode reaction occurred here is significantly different from that occurred on GSH SAM modified gold electrode. That is, the large peak at about 0.02 V is the redox of Cu 2 /Cu(Hg) that does not exist on the gold surface [13]. Although the À SH group could also be used to combine with Cu 2 , the addition of GSH before or after the addition of Cu 2 brings about a similar CV, which suggests the GSH molecules can still be adsorbed on the electrode surface [28,29].…”

Binding of Cd2+ and Zn2+ with the Phytochelatin (γ‐Glu‐Cys)4‐Gly: A Voltammetric Study Assisted by Multivariate Curve Resolution and Electrospray Ionization Mass Spectrometry

“…This implies not only some methodological adaptations of the original method but also some conceptual changes in data interpretation [13,14]. MCR-ALS has been applied to several voltammetric techniques, including cyclic voltammetry [15], and to a variety of metal complex systems such as those of Cd 2þ and Zn 2þ with a-and b-metallothionein (MT) domains [16], PC 2 [8] and PC 3 [17].…”

Conformational and Structural Changes of Choline Oxidase from Alcaligenes Species by Changing pH Values

“…35 Multivariate curve resolutions (MCR) are part of a family of chemometrics methods that deal with complex chemical equilibria through an evolutionary process. 36,37 For these reasons, we employed multivariate curve resolution method to study the effect of pH on the structure of choline oxidase.…”