This domain is found at the C-terminus of hydrogenase small subunits including periplasmic [NiFeSe] hydrogenase small subunit, uptake hydrogenase small subunit and periplasmic [NiFe] hydrogenase small subunit. This C-terminal domain binds two of the three iron-sulfur clusters in this enzyme [1-3].

1: The crystal structure of the [NiFe] hydrogenase from the photosynthetic bacterium Allochromatium vinosum: characterization of the oxidized enzyme (Ni-A state). Ogata H, Kellers P, Lubitz W; J Mol Biol. 2010;402:428-444. PMID:20673834

2: Crystal structure of the nickel-iron hydrogenase from Desulfovibrio gigas. Volbeda A, Charon MH, Piras C, Hatchikian EC, Frey M, Fontecilla-Camps JC; Nature 1995;373:580-587. PMID:7854413

3: The crystal structure of a reduced [NiFeSe] hydrogenase provides an image of the activated catalytic center. Garcin E, Vernede X, Hatchikian EC, Volbeda A, Frey M, Fontecilla-Camps JC; Structure. 1999;7:557-566. PMID:10378275