RESUMEN
The preparation, electrochemical characterization, and analytical applications of glassy carbon (GC) electrodes modified with electropolymerized films of the cation N,N'-di(3-pyrrol-1-yl-propyl)-4,4'-bipyridine (DPPB) are described. Electropolymerized films of DPPB on GC electrodes exhibit two one-electron redox processes centered at -0.45 and -0.85 V, respectively. S-Nitrosoglutathione (GSNO) can be electrocatalytically reduced at electrodes modified with electropolymerized films of DPPB at approximately -0.4 V vs sodium-saturated calomel electrode, which represents a dramatic diminution of about 600 mV in the overpotential in comparison with the reaction carried out at a bare GC electrode. The kinetics of the catalytic reaction have been characterized using cyclic voltammetry and rotated disk electrode techniques from which a value of (1.3 +/- 0.2) x 10(3)M-1 s-1 was obtained. Using electrodes modified with an electropolymerized film of DPPB we have carried out preliminary studies of the determination of intracellular GSNO concentrations in two strains of the bacterium Rhodobacter sphaeroides.
Asunto(s)
Electroquímica/métodos , Electrodos , Glutatión/análogos & derivados , Compuestos Nitrosos/análisis , Compuestos de Piridinio/química , Pirroles/química , Rhodobacter sphaeroides/química , Electroquímica/instrumentación , Glutatión/análisis , Glutatión/metabolismo , Glutatión/farmacología , Cinética , Nitroprusiato/farmacología , Compuestos Nitrosos/metabolismo , Compuestos Nitrosos/farmacología , Oxidación-Reducción , Compuestos de Piridinio/síntesis química , Pirroles/síntesis química , Reproducibilidad de los Resultados , S-NitrosoglutatiónRESUMEN
The preparation and electrochemical characterization of glassy carbon electrodes (GCEs) modified with electropolymerized films of the cation N-(3-pyrrol-1-yl-propyl)-4,4'-bipyridine (PPB) are described. The behavior of a new biosensor, which exhibits a high catalytic activity for nitrite reduction and which consists of a maltose binding protein nitrite reductase fusion (MBP-Nir) immobilized on an electropolymerized film of PPB as an electrocatalyst, is also described. The insoluble perchlorate salt of the poly(benzyl viologen) dication was used to immobilize MBP-Nir onto an electrode previously modified with an electropolymerized film of PPB. The electropolymerized film of PPB on the GCE is redox active and exhibits special electron-transfer properties toward the MBP-Nir layer but not toward Nir (Nir without MBP fusion attached), suggesting an intimate interaction between the PPB film and the MBP-Nir layer. The kinetics of the catalytic reaction between the biosensor and nitrite anion were characterized using cyclic voltammetry and rotated disk electrode techniques, and a value of (4.6 +/- 0.5) x 10(3) M-1 S-1 was obtained for the rate constant.