[NiFe]-hydrogenase, large subunit (IPR029014)
Short name: NiFe-Hase_large
- NADH-quinone oxidoreductase, subunit D (IPR001135)
- Nickel-dependent hydrogenase, large subunit (IPR001501)
- NADH:ubiquinone oxidoreductase, 49kDa subunit, conserved site (IPR014029)
- Coenzyme F420 hydrogenase, subunit alpha (IPR017682)
- Nickel-dependent hydrogenase, large subunit, nickel binding site (IPR018194)
- NAD(P)H-quinone oxidoreductase subunit D/H (IPR022885)
- NADH dehydrogenase, subunit CD (IPR023062)
- NADH-quinone oxidoreductase subunit CD (IPR026662)
- NADH-quinone oxidoreductase, subunit D superfamily (IPR038290)
Hydrogenases catalyse the reversible oxidation of molecular hydrogen and play a vital role in anaerobic metabolism. Metal-containing hydrogenases are subdivided into three classes: Fe ('iron only') hydrogenases; Ni-Fe hydrogenases; and Ni-Fe-Se hydrogenases [PMID: 3078655]. Hydrogen oxidation is coupled to the reduction of electron acceptors (such as oxygen, nitrate, sulphate, carbon dioxide and fumarate), whereas proton reduction (hydrogen evolution) is essential in pyruvate fermentation or in the disposal of excess electrons.
The Ni-Fe hydrogenases, when isolated, are found to catalyse both hydrogen evolution and uptake, with low-potential multihaem cytochromes, such as cytochrome c3, acting as either electron donors or acceptors, depending on their oxidation state. Both periplasmic (soluble) and membrane-bound hydrogenases are known.
The Ni-Fe hydrogenases are heterodimeric proteins consisting of small (S) and large (L) subunits. The small subunit contains three iron-sulphur clusters (two [4Fe-4S] and one [3Fe-4S]); the large subunit contains a nickel ion [PMID: 1558764]. Small subunits of membrane-bound Ni-Fe hydrogenases contain a C-terminal domain of about 40 residues that is absent in periplasmic forms.