Isolation and Characterization of an Anti-Insect β-Toxin from the Venom of the Scorpion Isometrus maculatus

Im-3 was isolated from the venom of the scorpion Isometrus maculatus through several steps of HPLC fractionation based on the insect paralytic activity. Injecting Im-3 into crickets induced paralysis, but no toxicity was apparent in mice after an intracerebroventricular injection. Im-3 shares sequence similarity to scorpion β-toxins that specifically affect insect sodium channels.