Cone snails are tropical marine predatory molluscs,and there is an unprecedented variety of neuropharmacologically active peptide.Over seventy living species of cone snails are distributed in China.The ve-nom of Conus caracteristicus collected from South China Sea was studied in this work.A new conotoxin,cr5a,was isolated from the venom through Sephadex G-25 chromatography and HPLC,and then was identified by（amino） acid analysis,mass spectrometry,N-terminal sequence.The primary structure of cr5a was CCKFQFLNFCCNE,it shared a conserved T-superfamily of conotoxins arrangement of cysteine residues（CC-CC）.Total chemical synthesis of the two possible disulfide linkages of cr5a was achieved,and the result of HPLC co-elution showed that cr5a was a tridecapeptide with a disulfide connectivity of Cys1-Cys10, Cys2-Cys11.So cr5a is a new member of the T-superfamily conotoxins.
