title: [Characterisation of a novel toxin active on potassium apanaine channels, purified from Buthus occitanus tunetanus scorpion venom].
abstract: A new peptidyl inhibitor of the small-conductance Ca(2+)-activated K+ channels (SKca) was purified to homogeneity from the venom of the Tunisian scorpion Buthus occitanus tunetanus. The molecular mass determined by SDS-PAGE, shows that it's a short peptide (3300 Da). The primary sequence of this toxin shows that it is a 31-residue polypeptide cross-linked by three disulfide bridges and structurally related to subfamily 5 of short scorpion toxins. This molecule shows similar pharmacological properties with this group of peptides inducing high toxicity in mice after intracerebro-ventricular injection, and competing with iodinated apamin for binding to its receptor site from rat brain synaptosomes (K0.5 = 4 nM).
authors.affiliation: Laboratoire des Venins et Toxines, Institut Pasteur de Tunis, BP 74, 1002 Tunis-Belvédère, Tunisie.
authors.forename: B
authors.initials: B
authors.lastname: Mahjoubi-Boubaker
authors.forename: M
authors.initials: M
authors.lastname: El Ayeb
authors.forename: R
authors.initials: R
authors.lastname: Kharrat
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001681:Biological Assay; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D015221:Potassium Channels / Q000187:drug effects*; D024681:Potassium Channels, Calcium-Activated / Q000037:antagonists & inhibitors*; D051381:Rats; D012604:Scorpion Venoms / Q000009:adverse effects / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D017386:Sequence Homology, Amino Acid; D013053:Spectrophotometry; D013574:Synaptosomes / Q000187:drug effects; D014416:Tunisia
chemical_list: C102637:BotIT2 toxin; D015221:Potassium Channels; D024681:Potassium Channels, Calcium-Activated; D012604:Scorpion Venoms; C033799:apamin receptor