Fig. 5. Caspase activity and effects of inhibition of caspase activity. (A) Number of cells undergoing apoptosis-like death under different treatments. Symbols: j, treated with 4 mM H₂O₂; cells preincubated with CED-3/CPP32 group of protease inhibitor Z-DEVD-FMK (m, 1 µM; r, 10 µM; ., 25 µM) and 4 mM H₂O₂; d, control without any treatment. (B) Caspase activity in cell lysates with or without inhibitor treatment. Cell lysates were from L. donovani promastigotes at 30 minutes after exposure to 4 mM H₂O₂. Z-DEVD-FMK was used as a caspase-like protein inhibitor. Results are mean ± s.e.m. of three experiments. (C) Time course of PARP-like protein cleavage during H₂O₂-induced apoptosis in L. donovani promastigotes shown on western blots with anti-PARP antibody at different time points after H₂O₂ induced stress. Lanes: m, marker; 1, 0 hour; 2, 1 hour; 3, 2 hours; 4, 4 hours; 5, 6 hours. (D) PARP-like protein cleavage induced by H₂O₂ in the presence of a caspase inhibitor at 4 hours of treatment. Lanes: 1, with 4 mM H₂O₂ treatment; 2, control without treatment; 3, cells preincubated with 1 µg of Z-DEVD-FMK prior to exposure to 4 mM H₂O₂. Result is representative of three experiments.