Functional characterization of a serine protease from Crotalus durissus collilineatus highly expressed in Pichia pastoris: Comparison to its native form

s / Toxicology Letters 229S (2014) S40–S252 S55 intracellular levels of Ca2+, ATP and total glutathione (tGSH) were also investigated (concentration range 0–1000 M). The cell death mode was evaluated by staining cells with annexin V/PI. TFMPPwas themost toxic of the tested drugs; EC50 values ( M) were 388.7, 20.3, 186.3, and 123.6 for BZP, TFMPP, MeOPP and MDBP, respectively. Significant decreases in tGSH and increases in the intracellular Ca2+ levels and M were observed for all drugs. Intracellular ATP levels remained unaltered, which was consistent with the high number of early apoptotic cells observed under fluorescence. These data brings support to the concerns raised on the risks associated with the abuse of these designer drugs. Given that TFMPP and BZP are frequently abused, often in association, and have been implicated in human intoxications, further studies are needed to better elucidate the mechanisms involved. Acknowledgements: Capes Foundation and FCT. http://dx.doi.org/10.1016/j.toxlet.2014.06.225