1
Extracts of CO-autotrophically grown cells of Acinetobacter sp. 1 were shown to use thionin, methylene blue, or 2,6-dichlorophenol-indophenol, but not NAD, NADP, FAD, or FMN, as electron acceptors for the oxidation of CO under strictly anaerobic conditions. The CO dehydrogenase (CO-DH) in the this bacterium was found to be an inducible enzyme. The enzyme activity was determined by an assay based on the CO-dependent reduction of thionin. Maximal reaction rates were found at pH 7.5 and 60°C, and the Arrhenius plot revealed an activation energy of 6.1 kcal/mol (25.5 kJ/mol). The Km for CO was 154,uM. Known metal chelating agents tested had no effects on the CO-DH activity. No divalent cation tested affect the enzyme activity significantly except Cue* which suppressed the activity completely. The enzyme was inhibited by glucose and succinate. The same extracts catalyzed oxidation of hydrogen gas and formate with thionin as electron acceptor. The CO-DH of Acinetobacter sp. 1 was found to have no immunological relationship with that of Pseudomonas carboxydohydrogena
|