Isolation and characterization of a novel toxin from the venom of the scorpion Centruroides limpidus limpidus Karsch

Abstract

A novel peptide, toxic to mice, was purified from the venom of the Mexican scorpion Centruroides limpidus limpidus, by means of gel filtration and ion exchange chromatography, followed by high performance liquid chromatography (HPLC). The complete amino acid sequence was determined by automatic Edman degradation of reduced and alkylated toxin, and by overlapping sequences of fragments of the toxin, generated by cleavage with proteinase V8 separated by HPLC. This toxin is composed of 66 amino acid residues, contains eight half-cystine residues, and is highly similar (91%) to the amino acid sequence deduced for toxin 1 of C. limpidus tecomanus and toxin 4 from C. noxius venom (89%). This peptide displaces the binding of radiolabeled toxin 2 of C. noxius from synaptosomal membranes of rat brain with superimposable kinetics, supporting the conclusion that it belongs to the β-scorpion toxin class. Further characterization of C. l. limpidus toxin 1, as we have named it, was performed by means of competition experiments with monoclonal antibodies and various purified scorpion toxins, using an ELISA assay. A panel of six distinct monoclonal antibodies (mAB) against toxin 2 and 3 of C. noxius was used. From these, only three clones, originally named BCF1, BCF8 and BCF9, were able to recognize toxin 1 from C. l. limpidus.