Electrocatalysis of the hydrogen production by [Fe] hydrogenase from Desulfovibrio vulgaris Hildenborough

Hydrogenases are enzymes which catalyze hydrogen production/consumption reactions. In this paper, the [Fe] hydrogenase from Desulfovibrio vulgaris Hildenborough is shown to catalyze the direct hydrogen production from protons, in the absence of any promoter, at a basal pyrolytic graphite electrode using cyclic voltammetry techniques. The effect of several parameters upon catalytic current is investigated: pH, hydrogenase concentration, ionic strength, competition with another protein (bovine serum albumin), cycling repetition, mode of electrode polishing. The extent and efficiency of the hydrogenase electroactivity are examined in the presence of either an artificial electron carrier (methylviologen) or a physiological partner cytochrome c3 isolated from the same bacterial strain. Results suggest that the electron-transfer process is essentially controlled by a complex between both hydrogenase and cytochrome c3. Electrocatalysis appears to be largely governed by the adsorption of hydrogenase on the electrode surface very likely involving hydrophobic interactions.