Purification and characterization of catalase-1 from Bacillus subtilis

The catalase activity produced in vegetative Bacillus subtilis, catalase-1, has been purified to homogeneity. The apparent native molecular weight was determined to be 395,000. Only one subunit type with a molecular weight of 65,000 was present, suggesting a hexamer structure for the enzyme. In other respects, catalase-1 was a typical catalase. Protoheme IX was identified as the heme component on the basis of the spectra of the enzyme and of the isolated hemochromogen. The ratio of protoheme/subunit was 1. The enzyme remained active over a broad pH range of 5-11 and was only slowly inactivated at 65 degrees C. It was inhibited by cyanide, azide, and various sulfhydryl compounds. The apparent Km for hydrogen peroxide was 40.1 mM. The amino acid composition was typical of other catalases in having relatively low amounts of tryptophan and cysteine.