Fig. 1. Effect of pH on free (open symbol) and immobilized (closed symbol) beta-amylase activity (A) and stability (B). The effect of pH on the enzyme activity (A)was measured at 50◦C. The effect of pH on enzyme stability (B) was measured as detailed in Methods. The enzyme preparations were incubated at different pH values for 30 min at room temperature (25◦C), and the remaining activity was assayed in pH 6.0, at 50◦C (initial activity is regarded as 100%). For all measurements were use dcitratephosphate buffer (pH 3.0–8.0) and Glicin-NaOH buffer (pH 9.0–10.0).