A new insect neurotoxin AngP(1) with analgesic effect from the scorpion Buthus martensii Karsch: purification and characterization

An insect toxin named BmK AngP1 was purified from the venom of the scorpion Buthus martensii Karsch (BmK). It also shows an evident analgesic effect o n mice, but is interestingly devoid of mammalian toxicity. Bioassay showed that the CPU value of AngP1 was 0.01 mug/body (approximate to 30 mg) for th e excitatory insect toxicity and 43.0% inhibition efficiency for analgesia at a dose of 5 mg/kg. However, even at the dosage of 10 mg/kg no detectable toxicity on mice could be found. The isoelectric point (pl) value for AngP 1 was 4.0, and its molecular mass analyzed by MALDI-TOF MS was 8141.0. The first 15 N-terminal residues of AngP1 were determined by Edman degradation and showed high similarity to that of other excitatory scorpion insect toxi ns. The circular dichroism spectroscopy measured on a JASCO J-720 system sh owed that there were 10.4% alpha -helix, 46.2% beta -strand and 14.1% turn structure in this peptide. Under two conditions single crystals of AngP1 we re obtained.