Scyllatoxin is one of the components of the venom of the Israeli scorpion‘Leiurus quinquestriatus hebraeus’. It consists of only 0.02% of the total protein in crude venom.[1]
Leiurotoxin I is a 31-residue peptide (sequence AFCNLRMCQLSCRSLGLLGKCIGDKCECVKH-NH2), with a helix and a short antiparallelβ-sheet. This toxin is stabilized by disulfide bonds: Cys8-Cys26 and Cys12-Cys28 is bound to the β-sheet, while Cys3-Cys21 is bound to an N-terminal segment preceding the helix. Leiurotoxin adopts the ά/β motif.[1] Especially the positively charged residues (Arg6 and Arg13, which are located in the ά helix) are important for the expression of toxin biological activities[2] and for its receptor affinity.[3]
Scyllatoxin is a blocker of small-conductance Ca2+– activated K+ channels at 10−13–10−11 M concentrations in various cell types.[1]
This toxin shows similarity in its physiological activity and binding specificity to apamin,[1] but both toxins show no structural similarity.[4]
^ abcdeZhu Q, Liang S, Martin L, Gasparini S, Ménez A, Vita C (September 2002). "Role of disulfide bonds in folding and activity of leiurotoxin I: just two disulfides suffice". Biochemistry. 41 (38): 11488–94. doi:10.1021/bi026136m. PMID12234192.
^Sabatier JM, Lecomte C, Mabrouk K, et al. (August 1996). "Synthesis and characterization of leiurotoxin I analogs lacking one disulfide bridge: evidence that disulfide pairing 3-21 is not required for full toxin activity". Biochemistry. 35 (33): 10641–7. doi:10.1021/bi960533d. PMID8718853.
^Buisine E, Wieruszeski JM, Lippens G, Wouters D, Tartar A, Sautiere P (June 1997). "Characterization of a new family of toxin-like peptides from the venom of the scorpion Leiurus quinquestriatus hebraeus. 1H-NMR structure of leiuropeptide II". The Journal of Peptide Research. 49 (6): 545–55. doi:10.1111/j.1399-3011.1997.tb01162.x. PMID9266482.
^Auguste P, Hugues M, Mourre C, Moinier D, Tartar A, Lazdunski M (January 1992). "Scyllatoxin, a blocker of Ca2+-activated K+ channels: structure-function relationships and brain localization of the binding sites". Biochemistry. 31 (3): 648–54. doi:10.1021/bi00118a003. PMID1731919.
