hydrogenase

A hydrogenase is an enzyme that catalyses the reversible oxidation of molecular hydrogen (H2), as shown below:

Hydrogen oxidation () is coupled to the reduction of electron acceptors such as oxygen, nitrate, ferric ion, sulfate, carbon dioxide (), and fumarate. On the other hand, proton reduction () is coupled to the oxidation of electron donors such as ferredoxin (FNR), and serves to dispose excess electrons in cells (essential in pyruvate fermentation). Both low-molecular weight compounds and proteins such as FNRs, cytochrome c3, and cytochrome c6 can act as physiological electron donors or acceptors for hydrogenases.