The decomposition of sodium formate by bacterium coli in the presence of heavy water

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Abstract
The isotopic composition of the H evolved from mixtures of heavy and ordinary water with sodium formate by the action of the dehydrogenase in Bacterium coli was analyzed by a microthermal conductivity method. The composition of the liberated hydrogen was determined by the equilibria H2 + D22HD, H2O + D2O2HDO and H2O + HDHDO + H2. The equilibrium constant of the latter reaction K= ([HDO][H2])/([H2O][HD]) at room temp. was about 3. Bact. coli also catalyzed the establishment of these equilibria between the molecular species H2, D2, HD, H2O, D2O and HDO in the absence of Na formate. Palladium black behaved similarly in decomposing Na formate and in catalyzing these equilibria. The decomposition of the formate by the hydrogenlyase of Bact. coli evidently occurred through atomic reactions and the primary formed H and D atoms exchanged with the H and D atoms of the water before combining to form hydrogen molecules.