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

Hydrogenases are enzymes which catalyze hydrogen production/consumption rea ctions. In this paper, the [Fe] hydrogenase from Desulfovibrio vulgaris Hil denborough is shown to catalyze the direct hydrogen production from protons , in the absence of any promoter, at a basal pyrolytic graphite electrode u sing cyclic voltammetry techniques. The effect of several parameters upon c atalytic current is investigated: pH, hydrogenase concentration, ionic stre ngth, competition with another protein (bovine serum albumin), cycling repe tition, mode of electrode polishing. The extent and efficiency of the hydro genase electroactivity are examined in the presence of either an artificial electron carrier (methylviologen) or a physiological partner cytochrome c( 3) isolated from the same bacterial strain. Results suggest that the electr on-transfer process is essentially controlled by a complex between both hyd rogenase and cytochrome c(3). Electrocatalysis appears to be largely govern ed by the adsorption of hydrogenase on the electrode surface very likely in volving hydrophobic interactions. (C) 2001 Elsevier Science BN. All rights reserved.