Tungsten cofactor

A family of enzymes that catalyze the molybdenum- or tungsten-cofactor dependent conversion of aldehydes to carboxylates, often using ferredoxin. See also Aldose Reductase... 

II. THE MOLYBDENUM AND TUNGSTEN COFACTORS II.A. Nomenclature and General Features... 

In addition to simple CEPT being a favored mechanistic possibility for poly sulfide reduction and formate oxidation, CEPT is almost certainly involved, in all cases, in the reactivation of the molybdenum and tungsten cofactor sites... 

B. Fischer and S. J. N. Burgmayer, Models for the Pyranopterin-Containing Molybdenum and Tungsten Cofactors, in Metal Ions in Biological Systems , eds. A. Sigel and H. Sigel, Marcel Dekker, New York, 2002, Vol. 39, p. 265. 

Acetogenic bacteria such as Clostridium (Cl.) ther-moaceticum or Cl. formicoaceticum catalyze an NADPH2-driven CO2 reduction to formate, which is further reduced via the tetrahydrofolate pathway to the -CH3 oxidation state, as the methyl is finally incorporated into acetic acid. This anabolic formate dehydrogenase has long been known to depend on the presence of Se in the medium for its formation. The enzyme is an ai 2 heterooligomer of 340 kDa the complex contains two selenocysteine residues, two moles of a tungsten cofactor, and Fe/S centers. 

In some prokaryotes the FDHs are complex enzymes which contain molybdenum or tungsten cofactors to transfer the electrons from formate oxidation to an independent active site, to reduce quinone, protons, or NAD(P) [82, 92]. These enzymes are suitable for adsorption onto an electrode, so that the electrode accepts the electrons from formate oxidation, and it may also donate electrons and drive... 

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