Study On The Structure-activity Relationship Of Conopeptide Conantokins, Isolation And Characterization Of The Conotoxins From Conus Textile In South China Sea

Conotoxins, which excreted from the venom gland of the venom canal, are mostly small, disulfide-rich peptides with 12~40 amino acids in length. Compared to other nature peptide toxins, conotoxins possess the superior chemical and pharmacological features, such as small molecular, stable structure, high activity and selectivity. Conotoxins can specifically target nicotinic acetylcholine receptors (AchRs), ion-channels and their subunits, such as calcium, sodium or potassium channel, and could be used as probes for the research of ion channel and receptor as well as new drugs or lead compounds. The purpose of the present paper was to probe the analgesic properties of conantokin peptides, isolate the conotoxins from Conus textile and probe the synthetic method of the conotoxins with one or three disulfide bonds.In the studies of analgesic activity of conantokin peptides, the following results were obtained: (1) 10 g ofγ,γ'-Di-butyl-Nα-9-fluorenylmethyloxycarbonyl-γ- carboxyglutamic acid for conantokin peptide synthesis was synthesized; (2) Con-G, con-T, con-Qu and 10 conantokin analogues were synthesized with modified methods, such as longer coupling time for the special amino acids; (3) Conantokins and variants were purified by gel filtration chromatography, ion exchange chromatography as well as reversed phase liquid chromatography (RP-HPLC) with 85% or more purity; (4) Analgesic activities of the 13 conantokins and variants were evaluated by several pain models. The results showed that conantokins with higher NR2B subunit selectivity exhibited higher analgesic activity, con-G[S16Y] had the highest analgesic ability compared to the nature peptide con-G and other conantokin peptides.The toxins of Conus textile from the South China Sea were isolated and identified. 11 conotoxins were obtained, 4 of them were first discovered, 7 of them had the similar amino acid sequences that come from Conus textile of Cebu and Marinduquc islands in Philippines or around areas of Vietnam Sea as reported by Olivera B M. The similar compositions of conotoxins of two specimen of the Conus textile suggest that they belong to same family. The special feature of conotoxins of Conus textile is the high content of M-family conotoxin with short amino acid sequence.To further study the conotoxins structure and other biological activities, other conotoxins with 1 or 3 disulfide bonds were synthesized. Conantokin variants with one disulfide bond were synthesized using DMSO oxidation system, N-calcium ion...