[Identification and isolation of the protein insect toxin (alpha-latroinsectotoxin from venom of the spider Latrodectus mactans tredecimguttatus].

The crude venom of spider Latrodectus mactans tredecimguttatus was fractionated by the combination of anion exchange and hydrophobic chromatography. The biological activity of fraction was tested by means of: 1) estimation of toxicity for housefly larva; 2) intracellular recording of miniature excitatory potentials (MEPSPs) in blowfly larvae muscle fibres. As a result of sequential procedures of chromatography separation a homogeneous protein of 120 kilodalton molecular weight was obtained. This protein referred to alpha-latroinsectotoxin produced: 1) a great increase of the frequency of MEPSPs in the dose of 4.2.10(-10) M and its paralytic dose for fly larva was approximately 20 ng/species; 2) no influence of the MEPSPs after application in the dose of 1.2.10(-7) M to the neuromuscular junction of the frog.