Further characterization of toxins T 1IV (TsTX-III) and T 2IV from Tityus serrulatus scorpion venom

Abstract

S. V. Sampaio, E. C. Arantes, W. A. Prado, F. Riccioppo Neto and J. R. Giglio. Further characterization of toxins T 1IV (TsTX-III) and T 2IV from Tityus serrulatus scorpion venom. Toxicon 29, 663–672, 1991.—Toxins T 1IV (TsTX-III) and T 2IV have been purified to homogeneity from Tityus serrulatus scorpion venom and further characterized. Their amino acid composition and SDS-PAGE reveal an approximate mol. wt of 7000. Their intracisternal ld 50 (μg/kg) in mice were 12.9±1.6 and 3.0±0.5, while their N-terminal amino acid sequences were K-E-G-Y-A-M-D-H-E-G-C-K-F-S- and K-E-G-Y-L-M-D-H-E-G-C-K-L-S-C-F-I-R-P-S-G-Y-C-G-R-E-, respectively. This sequence of T 2IV, its amino acid composition and its chromatographic and electrophoretic behaviour identify it as toxin γ (TsTX-I), which is the major toxin from this venom. TsTX-III (13 to 102 μg/kg) produced a long lasting enhancement of the hypertensive effect of noradrenaline and a slight decrease of the hypotensive effect of acetylcholine, while T 2IV (115 μg/kg) induced a prolonged hypotensive effect on the anesthetized rat. On the isolated guinea-pig vas deferens, TsTX-III (2.1 and 3.0 μg/ml) produced a horizontal shift of the dose-response curve for noradrenaline to the left with no change of the maximal response. At a concentration of 1.43 μM, it induced a prolongation of the duration of the B component of the compound action potential. This prolongation was strongly reduced after addition of tetrodotoxin.