ELECTROCATALYTIC REDUCTION OF S-NITROSOGLUTATHIONE AT ELECTRODES MODIFIED WITH AN ELECTROPOLYMERIZED FILM OF A PYRROLE-DERIVED VIOLOGEN SYSTEM AND THEIR APPLICATION TO CELLULAR S-NITROSOGLUTATHIONE DETERMINATIONS

The preparation, electrochemical characterization, and analytical appl ications of glassy carbon (GC) electrodes modified with electropolymer ized films of the cation N,N'-di(3-pyrrol-1-yl-propyl)-4,4'-bipyridine (DPPB) are described. Electropolymerized films of DPPB on GC electrod es exhibit two one-electron redox processes centered at -0.45 and -0.8 5 V, respectively. S-Nitrosoglutathione (GSNO) can be electrocatalytic ally reduced at electrodes modified with electropolymerized films of D PPB at approximately -0.4 V vs sodium-saturated calomel electrode, whi ch represents a dramatic diminution of about 600 mV in the overpotenti al 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(5) M-1 s(-1) was obtained. Using electrode s modified with an electropolymerized film of DPPB we have carried out preliminary studies of the determination of intracellular GSNO concen trations in two strains of the bacterium Rhodobacter sphaeroides. (C) 1998 Academic Press.