Isolation and Characterization of Staphylococcus Aureus Mf-31 Catalase (Enzyme, Protein)

167 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1984.S. aureus MF-31 catalase was purified to homogeneity using ethanol-chloroform fractionation, ammonium sulfate precipitation, ultrafiltration and gel filtration.The optimal pH for S. aureus MR-31 catalase was between pH 5 - pH 6. The enzyme was stable over the range pH 4 - pH 9. The apparent isoelectric point was 5.3 (+OR-) 0.01 pH units. With respect to temperature stability, S. aureus MR-31 was stable at 52(DEGREES)C after 45 minutes of heating. The enzyme was inactivated at 60(DEGREES)C for ten minutes, however this was dependent on the concentration of the enzyme and the presence of protectants. The apparent subunit molecular was 64,000 (+OR-) 1000 daltons, whereas the apparent native molecular weight was 235,000 (+OR-) 5000 daltons. Amino acid analysis revealed that S. aureus MF-31 catalase was similar to amino acid analyses of catalase from other sources. The iron content of S. aureus MF-31 catalase was found to be 0.089%, comparing favorably with other published findings. The enzyme was inhibited by millimolar concentrations of sodium cyanide, sodium azide and hydroxylamine, results indicating the presence of a heavy metal catalyst.The effects of salt, pH and salt concentration with heating on catalase activity of S. aureus MF-31 were examined. The results indicated that of the variables tested, pH played a major role. The chloride anion inhibited catalase activity at low pH. But this inhibition was influenced by the cation. Sodium chloride was more inhibitory at low pH than either potassium chloride or magnesium chloride.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD