Formate dehydrogenases are a set of enzymes that catalyse the oxidation of formate to carbon dioxide, donating the electrons to a second substrate, such as NAD+ in formate:NAD+ oxidoreductase (EC 1.2.1.2) or to a cytochrome in formate:ferricytochrome-b1 oxidoreductase (EC 1.2.2.1).[1][2]
Function
NAD-dependent formate dehydrogenases are important in methylotrophic yeast and bacteria and are vital in the catabolism of C1 compounds such as methanol.[3] The cytochrome-dependent enzymes are more important in anaerobic metabolism in prokaryotes.[4] For example, in E. coli, the formate:ferricytochrome-b1 oxidoreductase is an intrinsic membrane protein with two subunits and is involved in anaerobic nitrate respiration.[5][6]
NAD-dependent reaction
Formate + NAD+ ⇌ CO2 + NADH + H+
Cytochrome-dependent reaction
Formate + 2 ferricytochrome b1 ⇌ CO2 + 2 ferrocytochrome b1 + 2 H+
Molybdopterin, molybdenum and selenium dependence
One of the enzymes in the oxidoreductase family that sometimes employ tungsten (bacterial formate dehydrogenase H) is known to use a selenium-molybdenum version of molybdopterin.[7]
Transmembrane domain
The transmembrane domain of the beta subunit of formate dehydrogenase consists of a single transmembrane helix. This domain acts as a transmembrane anchor, allowing the conduction of electrons within the protein.
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