Alpha chain of the formate dehydrogenase (FDH) catalyze the reversible two-electron oxidation of formate to carbon dioxide. FDH loses activity in the presence of air, but this activity can be restored. The alpha subunit of formate dehydrogenase forms the active site. formate + NAD(+) = CO2 + NADH Binds 1 [4Fe-4S] cluster per subunit. Binds 1 W-bis(molybdopterin guanine dinucleotide) (W-bis-MGD) cofactor per subunit. Optimum pH is 7.5-8.0. Optimum temperature is 56 degrees Celsius. Heterodimer of alpha (FdhA) and beta (FdhB) subunits. The disulfide bond is likely to be broken in the active form of this enzyme. Predicted to be exported by the Tat system. The position of the signal peptide cleavage has been experimentally proven. Belongs to the prokaryotic molybdopterin-containing oxidoreductase family.