Crystal structure of the nickel-iron hydrogenase from Desulfovibrio gigas

The X-ray structure of the heterodimeric Ni–Fe hydrogenase from Desulfovibrio gigas, the enzyme responsible for the metabolism of molecular hydrogen, has been solved at 2.85 Å resolution. The active site, which appears to contain, besides nickel, a second metal ion, is buried in the 60K subunit. The 28K subunit, which coordinates one [3Fe–4S] and two [4Fe–4S] clusters, contains an amino-terminal domain with similarities to the redox protein flavodoxin. The structure suggests plausible electron and proton transfer pathways.