ELECTROCATALYSIS AT HYDROGENASE OR CYTOCHROME C-3-MODIFIED GLASSY-CARBON ELECTRODES

The immobilization of two redox proteins, hydrogenase and cytochrome c3 extracted from Desulfovibrio desulfuricans sulfate-reducing bacterium, on glassy carbon electrodes modified via carbodiimide procedure is reported. The catalytic activity at the hydrogenase-modified glassy carbon electrode is detected in the presence of methylviologen, which acts as a shuttle between immobilized hydrogenase and the electrode surface. The effect of experimental parameters (e.g., methylviologen concentration or pH) on the catalytic activity is examined; maximum activity is observed at pH 9.5. Catalytic activity is also detected when methylviologen is replaced by cytochrome c3, which is the physiological partner of hydrogenase. The cytochrome c3-modified glassy carbon does not yield a stable electrochemical response due to cytochrome c3 reconformation at the electrode surface.