Further characterization of toxins T1IV (TsTX-III) and T2IV from Tityus serrulatus scorpion venom.
Toxins T1IV (TsTX-III) and T2IV 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 LD50 (micrograms/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 T2IV, its amino acid composition and its chromatographic and electrophoretic behaviour identify it as toxin gamma (TsTX-I), which is the major toxin from this venom. TsTX-III (13 to 102 micrograms/kg) produced a long lasting enhancement of the hypertensive effect of noradrenaline and a slight decrease of the hypotensive effect of acetylcholine, while T2IV (115 micrograms/kg) induced a prolonged hypotensive effect on the anesthetized rat. On the isolated guinea-pig vas deferens, TsTX-III (2.1 and 3.0 micrograms/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 microM, 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.
Sampaio
S V
SV
Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, Brasil.
Arantes
E C
EC
Prado
W A
WA
Riccioppo Neto
F
F
Giglio
J R
JR
D000109:Acetylcholine / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects; D000595:Amino Acid Sequence; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004591:Electrophoresis, Polyacrylamide Gel; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009130:Muscle, Smooth / Q000187:drug effects; D009474:Neurons / Q000187:drug effects; D009498:Neurotoxins / Q000032:analysis* / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D011817:Rabbits; D051381:Rats; D011919:Rats, Inbred Strains; D012604:Scorpion Venoms / Q000032:analysis* / Q000494:pharmacology; D014630:Vagus Nerve / Q000166:cytology / Q000187:drug effects; D014649:Vas Deferens / Q000187:drug effects
D009498:Neurotoxins; D012604:Scorpion Venoms; C003609:tityustoxin; D000109:Acetylcholine; D009638:Norepinephrine