Fig. 3

(a) Optimal pH and (b) pH stability of PjxA and the three mutants. For pH stability, all proteins were pre-incubated at 40 °C for 30 min before measuring enzymatic activity. The amount of the enzyme was adjusted to 0.05 μg in each reaction. The sample controls without pre-incubation were defined as 100%. (c) Optimal temperature and (d) thermostability of PjxA and the three mutants. For thermal stability, all xylanases were incubated at 50 mM pH 5.5 sodium acetate buffer for 30 min before activity assay. The amount of the enzyme was adjusted to 0.05 μg in each reaction. The samples measures without pre-incubation were defined as 100%. Results are presented as means ± SD of duplicate experiments