Article

Electrochemical oxidation of selenocystine and selenomethionine.

Department of Chemistry, Jinan University, Guangzhou 510632, China.
Colloids and surfaces B: Biointerfaces (Impact Factor: 4.28). 08/2009; 74(1):150-3. DOI: 10.1016/j.colsurfb.2009.07.010
Source: PubMed

ABSTRACT Electrochemical oxidation of selenocystine (SeCys) and selenomethionine (SeMet), on a gold electrode was studied by cyclic voltammetry (CV), rotating disk electrode technique (RDE) and chronocoulometry (CC). In 0.2 mol/L HAc-NaAc (pH=3.90) supporting electrolyte, anodic peak I potential of SeCys and SeMet was 810 mV and 638 mV, respectively, and this electrode process was diffused controlled. The electrochemical oxidation process of SeCys, in which six electron-transfers were involved, yielded selenocystine selenoxide. The electrochemical oxidation process of SeMet, in which two electron-transfers were involved, yielded selemethionine selenoxide.

0 Bookmarks
 · 
75 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Selenium-containing compounds play an important role in antioxidant defense systems, binding to toxic metals, preventing their uptake into cells, and thus protecting cells from metal-induced formation of reactive oxygen species. Here, we present a proposal for a relatively new method as a complement to the more usual methods used in selenium studies. A systematic study of the metal-binding properties of selenocystine (SeCyst) in the presence of divalent metal cations (Cd, Co, Hg, Ni, and Zn) is reported. Isothermal titration calorimetry provides thermodynamic parameters of the systems. Titrations produced curves that could be fit reasonably well to the one set of sites model. The data clearly demonstrate that one M(2+) binds one SeCyst molecule, and the stable M(SeCyst) complex is formed under these conditions. The order of the SeCyst binding constant for the metal ions is Hg(2+) > Cd(2+) ~ Zn(2+) > Ni(2+)> Co(2+). Cadmium ion was selected as a modulator for the behavior of SeCyst in the presence of a nonessential metal, and zinc was selected for the case of an essential element. These interactions of SeCyst with Cd(2+) and Zn(2+), either individually or combined, were studied in aqueous buffered solutions at physiological pH by differential pulse polarography and circular dichroism spectroscopy. Furthermore, recently developed chemometric tools were applied to differential pulse polarography data obtained in mixtures of SeCyst and glutathione in the presence of Cd(2+) at physiological pH.
    European Journal of Biochemistry 02/2012; 17(2):321-9. · 3.16 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The behavior of selenocystine (SeCyst) alone or in the presence of various metal ions (Bi(3+), Cd(2+), Co(2+), Cu(2+), Cr(3+), Ni(2+), Pb(2+), and Zn(2+)) was studied using differential pulse voltammetry (DPV) over a wide pH range. Voltammetric data matrices were analyzed using chemometric tools recently developed for nonlinear data: pHfit and Gaussian Peak Adjustment (GPA). Under the experimental conditions tested, no evidence was found for the formation of metal complexes with Bi(3+), Cu(2+), Cr(3+), and Pb(2+). In contrast, SeCyst formed electroinactive complexes with Co(2+) and Ni(2+) and kinetically inert but electroactive complexes with Cd(2+) and Zn(2+). Titrations with Cd(2+), Co(2+), Ni(2+), and Zn(2+) produced data that were reasonably consistent with the formation of stable 1:1 M(SeCyst) complexes.
    The Journal of Physical Chemistry A 04/2012; 116(25):6526-31. · 2.77 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The complexation of Se-aminoacids selenomethionine (SeMet) and selenocystine (SeCyst) with Hg2+ was investigated by differential pulsed voltammetry (DPV) on Au-disk electrode. Complexation processes are proposed from the Gaussian Peak Adjustment analysis of DPV titration data. Main complexes were both 1:1 Hg:SeMet and Hg:SeCyst, although the formation of 2:1 complexes can be also proposed for Hg:SeCyst. Elimination voltammetry with linear scan was applied to investigate the adsorption of the ligands and the complexes on the Au surface.
    Electrochimica Acta 07/2011; 56(17):5988-5992. · 4.09 Impact Factor