Description_x000D_ Application_x000D_ Catalase from Sigma has been used as a positive control during the functional characterization of Clostridium difficile spore coat proteins._x000D_ Packaging_x000D_ 10, 25 mg in glass bottle_x000D_ Biochem/physiol Actions_x000D_ Catalase catalyzes the decomposition of hydrogen peroxide into water and oxygen. Each subunit of the tetramer contains iron bound to a protoheme IX group. The enzyme also strongly binds NADP, which is in close proximity to the heme group. Isoelectric point is found to be 6.5. Optimum pH for catalytic activity is 7.0. The enzyme activity is inhibited by 3-amino-1-H-1,2,4 triazole, cyanide, azide, hydroxylamine, cyanogen bromide, 2-mercaptoethanol, dithiothreitol, dianisidine, and nitrate. Incubation of catalase with ascorbate or ascorbate/Cu2+ results in degradation of the catalase molecule._x000D_ Caution_x000D_ Freezing of solutions is not recommended._x000D_ Unit Definition_x000D_ One unit will decompose 1.0 μmole of H2O2 per min at pH 7.0 at 25 °C, while the H2O2 concentration falls from 10.3 to 9.2 mM, measured by the rate of decrease of A240._x000D_ Physical form_x000D_ Suspension in 3.2 M (NH4)2SO4 solution, pH 6.0_x000D_ Analysis Note_x000D_ Protein determined by biuret