FIG. 6.

Phospholipases in T. cruzi amastigote and trypomastigote forms, active on PI and IPC. [³H]palmitic acid-labeled PI (A and B) and IPC (C and D) purified from T. cruzi epimastigotes were incubated for different times (5 min, lane 2; 15 min, lane 3; 1 h, lane 4; 2 h, lane 5; 18 h, lane 6) with a membrane fraction of amastigotes (A and C) or trypomastigotes (B and D). A supernatant of the membrane preparations was incubated for 18 h with the radioactive substrates (lane 7). A control consisting of the substrate incubated overnight with the buffer alone is shown in lane 1. A standard of [³H]palmitic acid is shown in lane 8. Incubations were performed with 250,000 cpm of substrate. After incubation the lipids were extracted as described under Materials and Methods and analyzed by TLC with solvent system B. The position of standards is indicated on the right. A, alkylglycerol; MAG, monoacylglycerol; C, ceramide. Characterization of compounds I to VI is described in Results.