title: Purification and characterization of a novel type of catalase from the bacterium Klebsiella pneumoniae.
abstract: A novel type of catalase, designated KpA, was purified from the bacterium Klebsiella pneumoniae. The enzyme is unique in that it is a dimer with subunit molecular weight of 80,000, it bears a chlorine-type heme as prosthetic group, and is active over a very wide range of H+ concentrations, with a plateau from pH 2.8 to 11.8. Yet, some properties of KpA are characteristic of typical catalases: it is stable when treated with with ethanol/chloroform, cannot be reduced by dithionite and it is inhibited by 3-amino-1,2,4-triazole and by the conjugate acid forms of azide and cyanide. The protein of KpA is outstandingly resistant to denaturing conditions: it retains full activity when incubated with 8 M urea, at 30 degrees C for 4 days, it is stable for 1 h at 70 degrees C and at pH values 3.1 and 11.5 and, when dialyzed against 50 mM H2O2, it still retains 42% of its activity after 80 min.
authors.affiliation: Department of Biochemistry, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Israel.
authors.forename: I
authors.initials: I
authors.lastname: Goldberg
authors.forename: A
authors.initials: A
authors.lastname: Hochman
mesh_terms: D000818:Animals; D001234:Aspergillus niger / Q000201:enzymology; D002374:Catalase / Q000037:antagonists & inhibitors / Q000302:isolation & purification* / Q000378:metabolism; D002417:Cattle; D002852:Chromatography, Ion Exchange; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007700:Kinetics; D007711:Klebsiella pneumoniae / Q000201:enzymology*; D008099:Liver / Q000201:enzymology; D046911:Macromolecular Substances; D008970:Molecular Weight; D013053:Spectrophotometry; D013816:Thermodynamics
chemical_list: D046911:Macromolecular Substances; D006861:Hydrogen Peroxide; D002374:Catalase