Isolation and characterization of TsTX-V, a new neurotoxin from Tityus serrulatus scorpion venom which delays the inactivation of Na+ channels.

Abstract

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 purified TsTX-V, which showed a single band by PAGE, SDS-PAGE or isoelectric focusing, a distinctive amino acid composition, mol. wt. = 7230, pI = 8.0 and i.v. LD50 = 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 microgram/ml. At 0.3 microgram/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+(15-30mM) 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.

• Authors: E C Arantes, F Riccioppo Neto, S V Sampaio, C A Vieira, J R Giglio
• Journal: Biochimica et biophysica acta (Biochim Biophys Acta) Vol. 1199 Issue 1 Pg. 69-75 (Jan 05 1994) ISSN: 0006-3002 [Print] Netherlands
• PMID: 8280757 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Amino Acids
• Neurotoxins
• Scorpion Venoms
• Sodium Channels

Topics

• Action Potentials
• Amino Acids (analysis)
• Animals
• Blood Pressure (drug effects)
• Lethal Dose 50
• Mice
• Molecular Weight
• Neurotoxins (chemistry, isolation & purification, pharmacology)
• Rabbits
• Rats
• Scorpion Venoms (chemistry, isolation & purification, pharmacology)
• Sodium Channels (drug effects)
• Vagus Nerve (drug effects)