Separation of hydrogenase-catalyzed hydrogen-evolution system from electron-donating system by means of enzymic electric cell technique.

An enzymic electric cell was constructed in which the anode was composed of a zinc plate inserted in aqueous NH(4)Cl solution and the cathode was composed of an electrode made of a glassy carbon stick inserted in a reaction mixture containing cytochrome c(3) hydrogenase (H(2):ferricytochrome c(3) oxidoreductase, EC 1.12.2.1) and methylviologen under an atmosphere of N(2). When the circuit was closed, the electric cell formulated as [Formula: see text] was composed, and hydrogenase-catalyzed H(2)-evolution was observed in the cathode of the cell with concomitant flow of an electric current. Thus, the hydrogenase-catalyzed reaction and the electron-donating reaction proceeded at different parts of the cell. This enables us to protect the hydrogenase from the byproducts of the electron-donating system, which might be hazardous to the enzyme.