Isolation, Purification and Enzymological Characterization of Catalase from Aloe

Objective: To obtain catalase from aloe and explore its enzymaological properties. Methods: Catalase was isolated and purified through fractional ammonium sulfate precipitation, ionexchange chromatography on DEAE-Sepharose, ion- exchange chromatography on CM-Sepharose and gel filtration on Sephacryl S-200. SDS-PAGE was used to identify the purity and relative molecular mass of the catalase. Results: Aloe catalase revealed a 228.05-fold purification and a recovery rate of activity of 14.10%. The specific activity of the purified aloe catalase was measured to be 17427.30 U/mg. Aloe catalase was characteristic of 239.90 kD relative molecular mass and 60.60 kD molecular mass of subunit. This demonstrates that the enzyme consists of four identical subunits. Moreover, the optimal reaction temperature and pH of the enzyme were 45 ℃ and 7.5, and its apparent Km towards hydrogen peroxide as the substrate was 34 mmol/L. Conclusion: Aloe catalase has been successfully isolated and purified, which exhibits excellent thermostability and acid-alkali tolerance.