Fig. 4

Activity of Trichobilharzia regenti cysteine peptidases after the treatment by nitric oxide and peroxynitrite. T. regenti cathepsins B1.1 (a) and B2 (b) were in vitro incubated with a fluorogenic substrate (E+S, the reference sample), 20 µM E-64 (the inhibitor of cysteine peptidases) and 0.1–10 μM NOR-3 (the donor of nitric oxide) or SIN-1 (the donor of peroxynitrite). The activity of both cathepsins was inhibited by treatment with 10 μM NOR-3 but enhanced after treatment with 0.1 μM SIN-1. The graphs show pooled data from three experiments, each performed in triplicates. Data were evaluated by Brown-Forsythe ANOVA and Dunnett’s T3 test; *P < 0.05, ***P < 0.001