Fig. 4.

The catalytic activity of NnV was dependent on pH, temperature and metal ions. NnV (2 mg/mL) was incubated under different (a) pH (3, 4, 5, 6, 7, 8, 9, 10 and 11), (b) temperatures (4, 25, 37, 60 and 100 °C) and (c) metal ions (Ca²⁺, Co²⁺, Cu²⁺, Mg²⁺, Mn²⁺, Zn²⁺ and Ni²⁺) and added to chymotrypsin substrate for 30 min at 37 °C. d NnV (20 μg) was submitted to fibrin zymography and incubated with metal ions (10 mM) in zymography reaction buffer for 18 h at 37 °C. The fibrin gel was stained with 0.125% Coomassie blue. Data represent as mean ± SD from the three fields *p < 0.05 and **p < 0.01, compared to control