Protease activity was measured at different pH values under
standard assay conditions, with azocasein as a substrate. The enzymatic
activity was assayed at pH 6.5–12.5 with 0.1 M phosphate
buffer (pH 6.5–7.5), 0.1 M Tris–HCl buffer (pH 7.2–9.0) and 0.1 M
NaOH/glycine buffer (pH 8.6–12.5). The effect of pH on the stability
of the enzyme preparation was studied by incubating the enzyme
at 25 C for 30 min with the above buffers and the enzymatic activities
were measured as described above, at 25 C, using the
0.1 M NaOH/glycine buffer (pH 11.0).