Separation and characterization of two catalase activities isolated from the yeast Trigonopsis variabilis

Two different catalases present in cell-free extracts of the yeast Trigonopsis variabilis have been separated by dye-binding chromatography. Both enzymes, named TvC-I and TvC-II, behave as members of the “typical catalases” family: they have a broad pH activity profile and do not possess peroxidase activity, are quite stable when treated with ethanol/chloroform mixtures, are inhibited by azide and cyanide at micromolar concentrations, and inactivated by 3-amino-1,2,4-triazole. Both enzymes are not thermostable, being inactivated rapidly at 55 °C, whereas their pH stability profile is markedly different. TvC-I is highly tolerant to pH variations, being rapidly inactivated only at acidic pH values (2.0. or lower). Its half-life time (t1/2) is at least 50 h at pH values between 3.0 and 12.0 and about 2 h at pH 13.0. At variance, the pH stability of TvC-II is markedly lower, the enzyme being rapidly inactivated at pH values lower than 4.0 and higher than 10.0. The t1/2 of TvC-II at pH values comprised between 6.0 and 10.0 is approximately 20 h, whereas at pH 4.0 and 5.0, t1/2 increases to 77 and 45 h, respectively.