The optimal pH for enzyme activities was determined at
50 ◦C at various pH levels (pH 3.0–12.0). Citric acid phosphate
buffer was used for pH 3.0–5.0, sodium phosphate was used
for pH 6.0–7.0, Tris–HCl was used for pH 7.5–9.0, and sodium
carbonate–bicarbonate was used for pH 10.0–12.0. For pH stability,
residual activity was measured at pH 7.5 after 1 h of incubation at
40 ◦C in the pH buffers being tested. Enzyme activities were tested
at temperatures ranging from 30 ◦C to 80 ◦C in 20 mM Tris–HCl
buffer (pH 7.5). The purified enzyme was incubated for 1 h at the
tested temperature, and residual activity was measured at 50 ◦C in
20 mM Tris–HCl buffer (pH 7.5).