Some properties of formate dehydrogenase.

In addition the enzyme catalyzes the oxidation of NADH by 0 2 . The stoichiometry of the first reaction is proved by the formation of the amount of NADH which under anaerobic conditions exactly corresponds to the amount of formate used. In this reaction NAD is replaceable by a large number of redox dyes. For the second reaction the stoichiometry is proved a) kinetically by the relation of the velocities of oxygen consumption with and without catalase (ratio 1 : 2 ) and b) by the amount of oxygen used for the oxidation of a given amount of formate with and without catalase (0.5 and 1 mole 0 2 per mole formate, respectively). The enzyme was isolated from formate/pyruvate grown bacteria4 by means of conventional steps (ammonium sulfate fractionations, chromatography on DEAE-cellulose and hydroxylapatite, and finally sucrose density gradient centrifugation or chromatography on Sephadex G150) at pH 5.6 under anaerobic conditions. In the last step two enzymatically active species were separated from each other from which the main species exhibits a molecular weight of about 300.000 ("FDH I " ) , the minor of about 200.000 daltons ("FDH II") as found by