HYDROGENASE, FORMATE DEHYDROGENASE AND CO DEHYDROGENASE-ACTIVITIES OFTHE THERMOPHILIC ANAEROBIC CARBOXYDOTROPHIC BACTERIUM CARBOXYDOTHERMUS-HYDROGENOFORMANS STRAIN-Z-2906

We have detected in the cells of the anaerobic, thermophilic carboxydo bacterium Carboxydothermus hydrogenoformans, strain Z-2906 highly acti ve lithotrophic metabolism enzymes: hydrogenase, formate dehydrogenase , and CO dehydrogenase, located in the cytoplasm. In its kinetic prope rties CO dehydrogenase was similar to the CO dehydrogenases of other a naerobes, but differed by an unusually high specific activity and ther mal stability. The maximum CO dehydrogenase activity was observed at 1 09-degrees-C and the K(M) for CO amounted to 20 muM. The half-lives of the enzyme were 35 min at 110-degrees-C and 6 min at 130-degrees-C. C arbon monoxide had a stabilizing and activating action on CO dehydroge nase.