Fig 5. Acid activation of cysteine endopeptidases from Tityus serrulatus´ MMG.

Effect of incubating MMG homogenate (A) at 30°C for 60 minutes under different pH conditions. (B) Effect of time on acidic activation of cysteine peptidases from Tityus serrulatus MMG homogenate. After incubation in acidic buffer (pH 2.6), 2 μl of each enzyme preparation was assayed in 200 μl of 0.1 M CP buffer (pH 5.5) with Z-FR-MCA to measure activity at constant pH. Activity increase was calculated as ratio of incubated enzyme activity over non-incubated control activity. All buffers used for activation (0.1 M CP, pH 2.6–7.0) and activity assays contained 3.0 mM cysteine and 3.0 mM EDTA.