PURIFICATION AND CHARACTERIZATION OF THE FORMATE DEHYDROGENASE FROM DESULFOVIBRIO-VULGARIS HILDENBOROUGH

Formate dehydrogenase from Desulfovibrio vulgaris Hildenborough, a sulfate-reducing bacterium, has been isolated and characterized. The enzyme is composed of three subunits. A high molecular mass subunit (83500 Da) is proposed to contain a molybdenum cofactor, a 27000 Da subunit is found to be similar to the Fe-S subunit of the formate dehydrogenase from Escherichia coli and a low molecular mass subunit (14000 Da) holds a c-type heme. The presence of heme c in formate dehydrogenase is reported for the first time and is correlated to the peculiar low oxidoreduction potential of the metabolism of these strictly anaerobic bacteria. In vitro measurements have shown that a monoheme cytochrome probably acts as a physiological partner of the enzyme in the periplasm.