Bothrops

Abstract: A myotoxin, bothropstoxin (BthTX), showing no detectable phospholipase A2 activity, was purified to homogeneity from the venom of the Brazilian snake Bothrops jararacussu by a combination of gel filtration on Sephadex G-75 and ion-exchange chromatography on SP-Sephadex C-25. Four phospholipases (SIII-SPI to SIII-SPIV) were also isolated, the latter showing, similarly to BthTX (SIII-SPV) myonecrotic activity. Approximate mol. wts, as determined by SDS-PAGE, and pI of SIII-SPI to SIII-SPIV are: 22,400−4.2; 15,500−4.8; 13,800−6.9; and 13,200−7.7, respectively. BthTX is a single chain protein, approximate mol. wt 13,000, with 16 half-cystine residues, pI = 8.2 and LD50 = 7.5 mg/kg (i.p.) and 4.8 mg/kg (i.v.) for 20 g mice. The ten first N-terminal amino acid residues show a significant homology to other toxins with phospholipase structure. BthTX is specifically myotoxic, contrary to crude B. jararacussu venom which, although also myotoxic, affects intramuscular arteries and veins leading to thrombosis. BthTX and SIII-SPIV also differ from toxins isolated from the venom of other Brazilian snakes which are strongly hemorrhagic.