In enzymology, a hydrogensulfite reductase () is an enzyme that catalyzes the chemical reaction trithionate + acceptor + 2 H2O + OH- 3 bisulfite + reduced acceptor The 4 substrates of this enzyme are trithionate, acceptor, H2O, and OH-, whereas its two products are bisulfite and reduced acceptor. This enzyme belongs to the family of oxidoreductases, specifically those acting on a sulfur group of donors with other acceptors. The systematic name of this enzyme class is trithionate:acceptor oxidoreductase. Other names in common use include bisulfite reductase, dissimilatory sulfite reductase, desulfoviridin, desulforubidin, desulfofuscidin, dissimilatory-type sulfite reductase, and trithionate:(acceptor) oxidoreductase. It has 4 cofactors: iron, sulfur, siroheme, and iron-sulfur. References EC 1.8.99 Iron enzymes Sulfur enzymes Siroheme enzymes Iron-sulfur enzymes Enzymes of unknown structure