Purification and partial characterization of a second toxin from the scorpion Tityus serrulatus

Ts1 from the Brazilian scorpion Tityus serrulatus: A half-century of studies on a multifunctional beta like-toxin

The Tityus serrulatus scorpion species represents a serious human health threat to in Brazil because it is among the animals that produces the most dangerous venoms for mammals in South America. Its venom has provided several highly selective ligands that specifically interact with sodium and potassium channels. During the past decades, several international groups published an increasing amount of data on the isolation and the chemical, pharmacological and immunological characterisation of its main β-toxin, Ts1. In this review, we compiled the best available past and recent knowledge on Ts1. Aside from its intricate purification, the state-of-the-art understanding concerning its pharmacological activities is presented. Its solved three-dimensional structure is shown, as well as the possible surface areas of contact between Ts1 and its diverse voltage-gated Na⁺ channel targets. Organisations of the gene and the precursor encoding Ts1 are also tackled based on available cDNA clones or on information obtained from polymerase chain reactions of stretches of scorpion DNA. At last, the immunological studies complete with Ts1 to set up an efficient immunotherapy against the Tityus serrulatus venom are summarized.

Venom variability among several Tityus serrulatus specimens

Individual differences in venom composition among several Tityus serrulatus specimens collected in the same area were examined by enzyme-linked immunosorbent assay (ELISA). Polyclonal antibodies raised against whole venom and against the alpha-type (toxin IV-5 or Ts IV) and the beta-type toxin (toxin gamma or Ts VII) were used to study specific variations in the venom. The ELISA results indicated clear differences among the scorpion venoms examined. The lethality (LD50) determined by subcutaneous injections of pooled venom with the same characteristics showed an interesting correlation between the expression level of each component studied and the lethal effect of the venom. Among the groups analysed, the group with the highest concentration of alpha-type toxin showed the highest toxicity. The groups with the lowest level of toxicity were those with a low concentration of alpha-type toxin. The results show that the lethality of the venom varies from specimen to specimen and suggest that alpha-type toxin must be the major lethal component in the whole venom.

Scorpion toxins from Centruroides noxius and Tityus serrulatus. Primary structures and sequence comparison by metric analysis

The complete primary structures of toxin II-14 from the Mexican scorpion Centruroides noxius Hoffmann and toxin gamma from the Brazilian scorpion Tityus serrulatus Lutz and Mello have been determined. Cleavage of toxin gamma after Met-6 with CNBr produced the 55-residue peptide 7-61, which maintained the four disulphide bonds but was not toxic to mice at a dose 3 times the lethal dose of native toxin gamma. Pairwise comparison by metric analysis of segment 1-50 of toxin gamma and the corresponding segments from two other South American scorpion toxins, five North American scorpion toxins, nine North African scorpion toxins and one Central Asian scorpion toxin showed that the three Brazilian toxins are intermediate between the North American and North African toxins. This result is consistent with the hypothesis that the South American and African continents were joined by a land connection in the distant past.