Two new arthropod toxins purified from the venom of the Mexican scorpion Centruroides nigrescens.

The venom of the slender black scorpion Centruroides nigrescens, from the State of Guerrero México, was fractionated by Sephadex G-50 gel filtration, followed by carboxymethyl cellulose ion separation and high-performance liquid chromatography, permitting to obtain two new peptides toxic to arthropods. The estimate LD50 of the soluble venom for the insect Acheta domesticus was 11.1 μg/g body weight, and for the arthropod Armadillidium vulgare was 61.1 μg body weight . The amino acid sequence of toxin Cnige1 (toxic to A. domesticus and A. vulgare) contains 65 amino acids, with a molecular mass of 7273.37 mass units, whereas toxin Cnige2, toxic to A. domesticus, contains 68 amino acids, with a molecular mass of 7548.81 units. Both peptides are well packed, containing 8 cysteines, which in the native venoms are forming 4 disulfide bridges each. The amino acid sequences found, for both novel toxins, shows some similarities to other known scorpion arthropod toxins. This venom is not toxic to mammalians, using mice as model, but contains many peptides as shown by mass spectrometry, for which the full primary structure and function are not known.