Effect of uncouplers on anaerobic adaptation of hydrogenase activity in [formula omitted

Abstract

An anaerobic incubation period of varying duration is required to induce hydrogenase activity in C. , reinhardtii . Inclusion of sodium acetate, a metabolizable carbonaceous substrate, in the medium during anaerobic incubation accelerates the activation process. Thus, in the presence of sodium acetate, hydrogen photoproduction is detected within 7 to 15 minutes after the onset of anaerobiosis. On the contrary, if an uncoupler of phosphorylation, such as CCCP or sodium arsenate, is present during anaerobic incubation, little activation of the hydrogenase is observed even after hours of anaerobic adaptation. Since the uncouplers had no inhibitory effect on hydrogen photoproduction by the alga when added to previously activated cells, they are not inhibitors of activated hydrogenase. The uncouplers interfere, most likely, with the activation of hydrogenase. Similar effects of uncouplers on the hydrogenase activation process were obtained using a cell-free assay of hydrogenase activity. These observations provide strong evidence that anaerobic activation of the hydrogenase is an energy requiring process.