Azadithiolate cofactor
# Azadithiolate cofactor

An azadithiolate cofactor is an anion with the formula $NH(CH_2S)_2^{2−}.$ It is used as a cofactor in the [FeFe] hydrogenases, bacterial enzymes responsible for the reversible reduction of 2 $H^+$ to $H_2.$ As a cofactor, the two thiolate functional groups are bound to each of the two irons in the active site of the enzyme in a bridging fashion. The amine functional group serves as an acid/base to transfer $H^+$ from the solution to the active site. The proton transfer function of this cofactor is of great importance to the activity of the hydrogenase enzyme, as $H_2$ evolution will not occur if the amine is not present.

