Figure 5

Characterization of purified CelA4 _F , CelA4 _T , CelA4 _D , and native CelA4. A: Effect of pH on β-1,4-glucanase activity. Activity assays were performed at 65°C for CelA4_F and CelA4_T, and at 60°C for CelA4_D, in buffers with pH values of 1.2 to 7.6. B: Effect of pH on stability. After incubating each enzyme at 37°C for 1 h in buffers with pH values between 1.2 and 9.2, activities were measured in 0.1 M citric acid-Na₂HPO₄ (pH 3.4, 65°C for CelA4_F and CelA4_T, and pH 2.6, 60°C for CelA4_D). C: Effect of temperature on β-1,4-glucanase activity measured in 0.1 M citric acid-Na₂HPO₄ (pH 3.4 for CelA4_F and CelA4_T, and pH 2.6 for CelA4_D). D: Thermostability assay. Each enzyme was incubated at 60, 65, or 70°C in 0.1 M citric acid-Na₂HPO₄ (pH 3.4 for CelA4_F and CelA4_T, and pH 2.6 for CelA4_D) for 1 h, and its activity was then measured under optimum conditions.