Influence of salt, pH and temperature on Staphylococcus aureus MF-31 catalase

Catalase (EC 1.11.1.6) from Staphylococcus aureus MF-31 was isolated. The purification procedure included ethanol-chloroform precipitation, ammonium sulfate fractionation, ultrafiltration and Sephadex G-200 column chromatography. The apparent native molecular weight was 235000 ± 5000. The enzyme was composed of four subunits, each having a molecular weight of 64 000 ± 1000. The purified enzyme had an apparent isoelectric point of 5·3 ± 0·1 pH units. The effects of salt, salt concentration, pH and temperature were examined for their influence on catalase stability. The enzyme was stable over the pH range of 4–9, and was inactivated at temperatures above 60°C. The inhibitory effects of salt were: NaCl > MgCl 2 > KCI. The combination of NaCl and low pH was the most inhibitory.