Purification and properties of the hydrogenase of Desulfovibrio desulfuricans.

Because of the relative simplicity of ita substrate, hydrogen, the enzyme hydrogenase is of particular interest in the study of the mechanism of enzyme catalysis. In its reaction with molecular hydrogen, hydrogenase simulates, in certain respects, the action of active platinum catalysts. It catalyzes the reduction by hydrogen of a variety of dyes and of various organic and inorganic compounds, and catalyzes the exchange reaction between hydrogen and heavy water, i.e. H) + HDO = HD + H20, and the conversion of para to ortho hydrogen (1). Inhibition studies on hydrogenase by Hoberman and Rittenberg (2) have suggested that iron was involved in the activity of the enzyme. The enzyme can be inactivated by carbon monoxide (2), nitric oxide (3), and various iron pentacyano compounds (4). Oxygen could inactivate the enzyme either by oxidation or oxygenation (5). The nature of the enzyme has been the subject of numerous investigations, the one point of general agreement being that a metal ion is involved in the action of the enzyme. The investigation of this aspect of the problem has been hampered by the difficulty in obtaining highly purified preparations of the enzyme. These difficulties are in part due to the particulate nature of the hydrogenase of many organisms. However, in the past few years organisms have been found which yield highly active soluble hydrogenase. Soluble hydrogenases have been prepared from Clostridium pasteurianum by Shug et al. (6), from Clostrtiiium butylicum by Peck and Gest (7), and from De.sulfovibrio desuljutians by Sadana and Jagannathan (8). Since the hydrogen activity of Desulf0vibri.o desulfuricans is high, we selected this organism for further study. In this report we shall describe the extraction in soluble form and purification of the hydrogenase of Desuljovibrio de.suljuricans and describe some of its properties.