PROTEOMIC ANALYSIS OF OPISTHACANTHUS CAYAPORUM SCORPION VENOM

ELISABETH FERRONI SCHWARTZ(1)

(1)Laboratório de Toxinologia, Universidade de Brasília, efschwa@unb.br

Many animals produce and secrete venoms used to their defense and/or to capture prey. Scorpion venom contains a large variety of active components such as peptides with 22-47 amino acid residues that recognize K+ channels and peptides with 58-76 residues that affect Na+ channels function. Both toxins are structurally related, adopting the “Cysteine Stabilized / motif” (Cs-motif), in which two strictly conserved disulfide bridges cross-link an alpha helix segment of the peptide with the second strand of an alpha-beta-beta minimum topology. These neurotoxins have played an important role as tools for the identification, purification, and functional characterization of voltage-gated ion channels. Another class of larger peptides containing 59-75 amino acid residues have also been described. This class is tightly folded by three disulfide bridges and show two structural domains: a linear N-terminus resembling cationic antimicrobial peptides and a Cysteine-rich C-terminus, with the consensus signature of Cs-motif, which is supposed to confer a K+ channel blocking activity to some of these peptides. Non-disulfide-bridged peptides are a different class of scorpion venom peptides exhibiting antimicrobial, hemolytic, bradykinin-potentiating and immune-modulating activities. Phospholipases may also be present in substantial amounts in scorpion venom. The Ischnuridae family includes the genera Opisthacanthus, Hadogenes and Cheloctonus which are not venomous to man, and a sting from one of them should, at worst, be no more than a bee sting. Due to its lower toxicity there have been few reports on the venom of scorpions from the Ischnuridae family. This family is distributed through Africa, south-east Asia, Australia and South America and associated islands. Opisthacanthus occurs in the Caribbean, Central and South Americas, Africa and Madagascar. The genus Opisthacanthus presents a gondwanian pattern of distribution. In Brazil, the family Ischnuridae is represented by two species of Opisthacanthus. O. cayaporum is endemic to open savannas in the eastern Amazonia (south of the State of Pará and State of Tocantins). In this conference it will be presented the fractioning of the O. cayaporum crude venom, showing the complex profile of molecular masses of its components. Besides, it will also be presented the purification of the main peptide components, their N-terminals sequences, and the biological activities of some of them.