a scorpion a-insect toxin, which prolongs the evoked action potential by an inhibition of sodium current inactivation in insects and mammals. LqhaIT serves as a marker for receptor site-3 on insect and mammalian sodium channels (2, 4-6).

65-amino acid polypeptide with 4 disulfide bridges produced in E.coli (1,2), originally from Leiurus quinquestriatus hebraeus venom (3).

• Molecular Weight : 7,380.4 Da.
  
  
• Solubility in : Well in water and saline.
  
  
• Purity min. : min. 96% (capillary electrophorensis).
  
  
• Biological Activity : Lqh aIT is highly toxic to insects; it also has a strong toxicity to mice by subcutaneous injection (but very weak by intraventricular route (4)). Lqh aIT causes an extreme prolongation of the action potential in both cockroach giant axon and rat skeletal muscle preparations as a result of the slowing and incomplete inactivation of the sodium currents (3,4). LqhaIT is very active on insect and skeletal muscle sodium channels expressed in Xenopus oocytes but is very weak on rat brain IIa channels (5,6).
  
  
• Toxicity (LD₅₀) : blowfly larvae: delayed sustained contraction paralysis (PU₅₀): 140 ng/g; isopods (terrestrial crustaceans): paralysis within 5 mn (PU₅₀): 200 ng/g; mice: lethality observed after 24 h (LD₅₀): 5 µg/kg.
  
  
• Storage recommendations : store at 4°C.
  
  
• CAS Reg. No. : 115422-61-2
  
  
• Bibliography :
  
  1. Tugarinov et al., (1997) Biochemistry 36,2414-2424. 2.
  2. Zilberberg et al., (1997) J. Biol. Chem. 272, 14810-14818.
  3. Eitan et al., Biochemistry (1990). 29:5941-5947
  4. Gordon et al., J. Biol. Chem. (1996) 271:8034-8045
  5. Karbat et al., (2004) J, Biol. Chem. 279, 31679-31686.
  6. Gilles et al., (2000) Eur. J. Neurosci. 12, 2823-2832