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

Nafion-coated glassy carbon electrodes containing the copper(II) compl ex prepared from the tripodal tris(pyrazol-1-ylmethyl)amine ligand are shown to effectively mediate electron transfer to cytochrome c and th e copper-containing enzyme tyrosinase. For both species, a concentrati on-dependent increase in cathodic current is observed at the peak pote ntial for the mediator following addition of protein to the buffer sol ution containing the modified electrode. The average increase for a cy tochrome 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 sec ond-order EC catalytic scheme in which the reduction of protein is med iated by the copper complex in Nafion.