Fig. 3

Enzymatic properties of recombinant prolyl endopeptidase. A The effect of pH on recombinant prolyl endopeptidase activity and stability. The pH optimum was determined between pH 3.0–8.0 at 37 ℃. The pH stability was determined by incubating the enzyme at the pH range of 1.0–11.0 at room temperature for 1 h and assayed at 37 ℃. B The effect of temperature on prolyl endopeptidase activity and stability. The activity for optimum temperature was determined between 20–80 ℃ at pH 4.0. The temperature stability was analyzed by incubating the enzyme for 1 h at the temperature range of 4–80 ℃. C The effect of various metals concentration on recombinant prolyl endopeptidase activity. The recombinant protein activity was analyzed after incubating with various metals at room temperature for 1 h. (*p < 0.05, **p < 0.01, ****p < 0.0001, ns: not significant). D The effect of alcohol on the activity of recombinant prolyl endopeptidase. Following the treatment with different concentrations of alcohol at 37 ℃ for 8 h, the residue activity of prolyl endopeptidase was determined at 37 ℃ and pH 4.0. All experiments were conducted in triplicate