Isolation and characterization of TsTX-V, a new neurotoxin from Tityus serrulatus scorpion venom which delays the inactivation of NA+ channels
1994
Arantes, E.C. | Neto, F.R. | Sampaio, S.V. | Vieira, C.A. | Giglio, J.R.
TsTX-V, a new neurotoxin from Tityus serrulatus scorpion venom able to induce a prolongation of the inactivation of Na(+) channels, has been purified to homogeneity. The venom was chromatographed on CM-cellulose-52 and 13 fractions were first collected. A subsequent stepwise elution chromatography of fraction XI afforded, among other toxins, highly TsTX-V, which showed a single band by PAGE, SDS-PAGE or isoelectric focusing, a distinctive amino acid composition, molecular wt.=7230, pI=8.0 and i.v.LD(50)= 94 +/- 7 micrograms/kg in mice. TsTX-V induced a long lasting hypertension in anesthetized rats and prolonged the action potential of the B fibers of the rabbit vagus nerve at 0.03 micrograms/ml. At 0.3 micrograms/ml and higher concentrations it caused also a nerve depolarization. These effects on nerve membranes were irreversible and could be suppressed by tetrodotoxin (200-500 nM). Nerve fibers depolarized by high extracellular K(+)(l5-30 millimoles) concentrations still displayed long duration action potentials after TsTX-V treatment. It is suggested that TsTX-V blocks the Na(+) channel inactivation system probably as an alpha-toxin.
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