NAD(P)+-dependent hydrogenase activity in extracts from the cyanobacteriumAnacystis nidulans

Sequence data had indicated that cyanobacteria might possess a bidirectional hydrogenase with properties similar to the soluble enzymes from Alcaligenes eutrophus, Nocardia opaca and Desulfovibrio fructosovorans. The present study shows that extracts from the cyanobacterium Anacystis nidulans catalyse NAD(P)H-dependent H2 evolution with low but significant activity and uptake of the gas with NAD(P)+ as the electron acceptor. NAD+ is the preferred electron acceptor and NADH the preferred donor compared to NADP+ and NADPH, respectively. Activity levels of this NAD(P)+dependent, bidirectional hydrogenase are too low to support chemoautotrophic growth in A. nidulans.