Characterization of a partially purified freeze dried mannanase from bacillus subtilis

The objective of the work was to determine the characteristics of the partially purified enzymes based on the pH (optimum and stability), temperature stability), effects on metal ions and protein concentration. (optimum and Ammonium sulfate precipitation method was used for partial purification, while crude enzyme was used for the preparation of freeze dried enzyme. The enzyme was optimally active at pH 5.5, and the activity was almost completely lost its activity at the pH of 2-3 while pH 2 for freeze dried enzyme. The enzyme stability was checked at different pH values between pH 2.0 to 10.0. After the samples were incubated at 50°C for 6 hours, it showed that the mannanase was stable at pH range between 5.0 and 7.0.
The optimum temperature for enzyme activity was determined by various range of temperature between 30°C to 90°C. The optimum temperature for the enzyme was 50°C and more stable at 40°C to 60°C. More than 80% of the residual activity retained at this temperature range. There was no significant difference in mannanase activity between the metal ions examined; K±, Mg2+, Ca2+, Cu24 Ba2+, Cs, Co and Na+ However, the activity was strongly inhibited by Cu2+ and Fe2+.The results showed that freeze dried was more stable compared to liquid enzyme as the enzyme activity still remained more than 50%.