MEDIATED ELECTROCHEMICAL REDUCTION OF CYTOCHROME-C AND TYROSINASE AT PERFLUOROSULFONATED IONOMER COATED ELECTRODES

Nafion-coated glassy carbon electrodes containing the copper(II) complex prepared from the tripodal tris(pyrazol-1-ylmethyl)amine ligand are shown to effectively mediate electron transfer to cytochrome c and the copper-containing enzyme tyrosinase. For both species, a concentration-dependent increase in cathodic current is observed at the peak potential for the mediator following addition of protein to the buffer solution containing the modified electrode. The average increase for a cytochrome c concentration of 0.19 mM is 11 +/- 3.2%, while that for 5.6 muM tyrosinase is 9.5 +/-4. 6%. The results are consistent with a second-order EC catalytic scheme in which the reduction of protein is mediated by the copper complex in Nafion.