A microbial enzyme complex which contains nickel and iron in its active site. In Acetomicrobium flavidum it is an alpha 2 beta 2 tetramer. [ GOC:tt GOC:mengo_curators http://www.ncbi.nlm.nih.gov/pubmed/8936309 ]
Synonyms: Ni-Fe hydrogenase complex nickel-iron hydrogenase complex