Investigating And Structure Identifying Of Novel Conotoxins From South China Sea

Conotoxins are biologically active peptides isolated from venomous marine cone snails. They are typically small disulfide-rich peptides containing 10-40 amino acid residues. These bioactive peptides are hypervariable and active on a number of receptors and ion channels. So far they have been categorized into seven superfamilies named A, I, M, O, P, S, and T, which are characterized by the number of their cysteine residues, the arrangement of the disulfide bonds and the distinctive and conserved signal region of the toxin precursor. Conotoxins are utilized as reasearch tools in many fields of neurobiology since they provide high-affinity antagonists for receptor and ion channel subtypes, and being small peptides, they are synthesizable and modifiable, thus increasing their availability and potential utility. As mentioned above they can be used both as pharmacological tools and as templates for drug design.Most of characterized conotoxins are mainly from fish-hunting conus as well as several molluscivorous species, because they were believed to be toxic to vertebrateIn this study, we investigated the venom of Conus marmoreus (molluscivorous species) and Conus vexllium(vermivorous species) from South China Sea by separating, purifying and protein sequencing technologies to character unknown conotoxins. And 26 toxins, that could be grouped into A-, M-, O-, T-superfamily and linear conopeptides respectively according to their primary structures, have been identified from the venom ducts of Conus marmoreus. Among them, toxins mr2 and mr1931 might own new functions to their novel structures, so the secondary structure of mr2 was charactered furtherly. Two toxins Vx6c and Vx6d with novel sequences was characterized from the venom ducts of Conus marmoreus. They are two new members of O-superfamily because of their disulfide bone frameworks, but they show low sequence homology with other O-superfamily members from molluscivorous or piscivorous species.The prey strategy of Conus marmoreus is analysed base on the investigation of conotoxins from its venom. The particularity of tow toxins from Conus vexllium also indicates different function or targets between vermivorous conus and piscivorous conus toxins.