title: Characterization of a manganese-containing catalase from the obligate thermophile Thermoleophilum album.
abstract: A manganese-containing catalase has been characterized from Thermoleophilum album NM, a gram-negative aerobic bacterium obligate for thermophily and n-alkane substrates. The level of catalase in cells was increased about ninefold by growth in the presence of paraquat (2.5 microM), a superoxide-generating toxicant. Superoxide dismutase levels were unaffected by this compound. The enzyme was purified from cultures grown in the presence of paraquat to greater than 95% homogeneity and had an Mr of 141,000. The enzyme was composed of four subunits, and each had an Mr of 34,000. There were 1.4 +/- 0.4 atoms of manganese present per subunit. The catalase had a Km for hydrogen peroxide of 15 mM and a Vmax of 11 mM/mg. Peroxidase activity, as measured with p-phenylenediamine, copurified with the catalase. Inhibitors of heme-catalase were weak inhibitors of the T. album enzyme. The optimum pH for catalase activity was 8 to 9. The enzyme was stable from pH 6.5 to 11 and retained activity at assay temperatures from 25 to 80 degrees C. The catalase was stable for 24 h of incubation at 60 degrees C.
mesh_terms: D002374:Catalase / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism*; D004790:Enzyme Induction; D006088:Gram-Negative Aerobic Bacteria / Q000201:enzymology*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008345:Manganese / Q000032:analysis; D008970:Molecular Weight; D010269:Paraquat / Q000494:pharmacology
chemical_list: D008345:Manganese; D002374:Catalase; D010269:Paraquat