Chong-Xu Fan

Beijing Research Institute of Chemical Industry, Peping, Beijing, China

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Publications (6)9.8 Total impact

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    ABSTRACT: AimTo study the chemical constituents of the venom of Conus betulinus that collected from South China Sea.Methods Gel chromatography and HPLC were applied to isolate toxins from the venom of Conus betulinus and a peptide toxin was obtained. Its chemical structure was characterized by mass spectrometry, amino acid analysis, N-terminal sequence and disulfide location. The structure was validated by comparison with natural and synthetic compounds.ResultsA conotoxin named conotoxin bt5a was isolated from the venom of Conus betulinus and its sequence is H-Ser-Gla-Cys-Cys-Ile-Arg-Asn-Phe-Leu-Cys-Cys-OH, in which Cys3 and Cys10, Cys4 and Cys11 form two intrachain disulfide bonds.Conclusion Conotoxin bt5a is a new member of T-superfamily conotoxins.
    Chinese Journal of Natural Medicines 01/2010; 8(2):132-136. DOI:10.3724/SP.J.1009.2010.00132
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    ABSTRACT: Cone snails are tropical marine mollusks that envenomate prey with a complex mixture of neuropharmacologically active compounds for the purpose of feeding and defence, each evolved to act in a highly specific manner on different parts of the nervous system. Here, we report the peptide purification, molecular cloning, chemical synthesis, and functional characterization of a structurally unique toxin isolated from the venom of Conus vexillum. The novel peptide, designated Vx2, was composed of 21 amino acid residues cross-linked by 3 disulfide bonds (WIDPSHYCCCGGGCTDDCVNC). Intriguingly, its mature peptide sequence shows low level of similarity with other identified conotoxins, and its unique motif (-CCCGGGC-) was not reported in other Conus peptides. However, its signal peptide sequence shares high similarity with those of the M-superfamily conotoxins. Hence, Vx2 could be classified into a new family of the M-superfamily.
    Peptides 05/2006; 27(4):682-9. DOI:10.1016/j.peptides.2005.08.004 · 2.61 Impact Factor
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    ABSTRACT: O-superfamily conotoxins include several families that have diverse pharmacological activity on Na+, K+ or Ca2+ channels. These superfamily toxins have been mainly found in fish-hunting and mollusk-hunting Conus species. Here, we reported two novel O-superfamily conotoxins, vx6a and vx6b, purified from a worm-hunting cone snail, Conus vexillum. Though their cysteine framework and signal peptides share high similarity with those of other members of O-superfamily, the mature vx6a and vx6b both have a low sequence homology with others. To test the biological function of vx6a, the toxin was chemically synthesized and then tested on the locust dorsal unpaired median (DUM) neuron system which containing various ion channels. Although no any activity on ion channels was found on the DUM neuron system, vx6a could clearly elicit a series of symptoms in mouse via intracranial injection, such as quivering, climbing, scratching, barrel rolling and paralysis of limbs at different dose.
    Toxicon 04/2006; 47(4):425-36. DOI:10.1016/j.toxicon.2005.12.007 · 2.58 Impact Factor
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    ABSTRACT: A novel conotoxin, kappa-conotoxin (kappa-BtX), has been purified and characterized from the venom of a worm-hunting cone snail, Conus betulinus. The toxin, with four disulfide bonds, shares no sequence homology with any other conotoxins. Based on a partial amino acid sequence, its cDNA was cloned and sequenced. The deduced sequence consists of a 26-residue putative signal peptide, a 31-residue mature toxin, and a 13-residue extra peptide at the C terminus. The extra peptide is cleaved off by proteinase post-processing. All three Glu residues are gamma-carboxylated, one of the two Pro residues is hydroxylated at position 27, and its C-terminal residue is Pro-amidated. The monoisotopic mass of the toxin is 3569.0 Da. Electrophysiological experiments show that: 1) among voltage-gated channels, kappa-BtX is a specific modulator of K(+) channels; 2) among the K channels, kappa-BtX specifically up-modulates the Ca(2+)- and voltage-sensitive BK channels (252 +/- 47%); 3) its EC(50) is 0.7 nm with a single binding site (Hill = 0.88); 4) the time constant of wash-out is 8.3 s; and 5) kappa-BtX has no effect on single channel conductance, but increases the open probability of BK channels. It is concluded that kappa-BtX is a novel specific biotoxin against BK channels.
    Journal of Biological Chemistry 05/2003; 278(15):12624-33. DOI:10.1074/jbc.M210200200 · 4.60 Impact Factor
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