EC 1.17.98.4     
Accepted name: formate dehydrogenase (hydrogenase)
Reaction: formate + an [oxidized hydrogenase] = CO2 + a [reduced hydrogenase]
Other name(s): FDHH; FDH-H; FDH-O; formate dehydrogenase H; formate dehydrogenase O
Systematic name: formate:[oxidized hydrogenase] oxidoreductase
Comments: Formate dehydrogenase H is a cytoplasmic enzyme that oxidizes formate without oxygen transfer, transferring electrons to a hydrogenase. The two enzymes form the formate-hydrogen lyase complex [1]. The enzyme contains an [4Fe-4S] cluster, a selenocysteine residue and a molybdopterin cofactor [1].
References:
1.  Axley, M.J., Grahame, D.A. and Stadtman, T.C. Escherichia coli formate-hydrogen lyase. Purification and properties of the selenium-dependent formate dehydrogenase component. J. Biol. Chem. 265 (1990) 18213–18218. [PMID: 2211698]
2.  Gladyshev, V.N., Boyington, J.C., Khangulov, S.V., Grahame, D.A., Stadtman, T.C. and Sun, P.D. Characterization of crystalline formate dehydrogenase H from Escherichia coli. Stabilization, EPR spectroscopy, and preliminary crystallographic analysis. J. Biol. Chem. 271 (1996) 8095–8100. [PMID: 8626495]
3.  Khangulov, S.V., Gladyshev, V.N., Dismukes, G.C. and Stadtman, T.C. Selenium-containing formate dehydrogenase H from Escherichia coli: a molybdopterin enzyme that catalyzes formate oxidation without oxygen transfer. Biochemistry 37 (1998) 3518–3528. [PMID: 9521673]
[EC 1.17.98.4 created 2010 as EC 1.1.99.33, transferred 2018 to EC 1.17.99.7, transferred 2020 to 1.17.98.4.]