The insect-selective neurotoxin(BmK IT) of scorpion Buthus martensi Karsch was first reduced and S-alkylated, and then digested by TPCK-trypsin and Staphylococcus aureus V-8 Protease. The enzymatic peptides were purif...The insect-selective neurotoxin(BmK IT) of scorpion Buthus martensi Karsch was first reduced and S-alkylated, and then digested by TPCK-trypsin and Staphylococcus aureus V-8 Protease. The enzymatic peptides were purified on TLC-plastic sheet and submitted to determine their amino acid compositions and sequences. The sequence of the 70 amino acid residues of BmK IT was established with reference to the primary structure of AaH IT, another excitatory insect-selective toxin from the venom of North African scorpion Androctonus australis Hector. About 75% of the homologous sequence was found in the molecules of BmK IT and AaH IT. It is obvious that the results contribute toward better understanding of the molecular structure characteristics, structure/activity relationship of scorpion insect-selective toxins, and they can serve as the molecular basis for utilizing the toxins as a tool to clarify molecular mechanism involved in channel gating, and to infer the possibility of developing them as new selective bioinsecticides.展开更多
Scorpion anti-insect toxins can be divided into long chain (about 61-70 aminoacid residues)and short chain (about 5 amino acid residues) types according to theirmolecular size, and the former can be further divided in...Scorpion anti-insect toxins can be divided into long chain (about 61-70 aminoacid residues)and short chain (about 5 amino acid residues) types according to theirmolecular size, and the former can be further divided into excitatory and depressanttypes on the basis of their pharmacological action. In our previous papers, the iso-lation and determination of the primary structure of an excitatory展开更多
Suitable pattern and high yield were obtained when the reverse-phase performance liquidchromatography (RP-HPLC) was used to separate neurotoxins from venom of Chinese scorpion Buthusmartensi Karsch.Using this techniqu...Suitable pattern and high yield were obtained when the reverse-phase performance liquidchromatography (RP-HPLC) was used to separate neurotoxins from venom of Chinese scorpion Buthusmartensi Karsch.Using this technique,the venom was first separated to two main regions.The toxicitytests show that the insect-selective neurotoxical components are concentrated in the latter region,from whichfive insect-selective neurotoxins designated by BmK IT1-IT5 were obtained.According to the results of thetoxicity test as well as the amino acid composition and N-terminal analyses,BmK IT1 is the excitatory insectneurotoxin as reported in a previous paper,and the others are the newly found depressant insect-selectiveneurotoxins.The molecules of all the four toxins are single-chain minipeptides of about 60 amino acids.Their isoelectric points (pI) are between 8.3 and 8.5.The fact that BmK IT2 loses completely its insect tox-icity after being modified by fluorochrome shows that the positive charges on the molecular surface of thiskind of toxins are important to maintaining the bioactivity of the molecules.展开更多
基金This research was supported by a fellowship from CNRS of France, granted to Ji Yong-hua,and in part by a grant for Youth Foundation(388008), the National Natural Science Foundation of China and the Grant-in-Aid for Overseas Scientific Research from the M
文摘The insect-selective neurotoxin(BmK IT) of scorpion Buthus martensi Karsch was first reduced and S-alkylated, and then digested by TPCK-trypsin and Staphylococcus aureus V-8 Protease. The enzymatic peptides were purified on TLC-plastic sheet and submitted to determine their amino acid compositions and sequences. The sequence of the 70 amino acid residues of BmK IT was established with reference to the primary structure of AaH IT, another excitatory insect-selective toxin from the venom of North African scorpion Androctonus australis Hector. About 75% of the homologous sequence was found in the molecules of BmK IT and AaH IT. It is obvious that the results contribute toward better understanding of the molecular structure characteristics, structure/activity relationship of scorpion insect-selective toxins, and they can serve as the molecular basis for utilizing the toxins as a tool to clarify molecular mechanism involved in channel gating, and to infer the possibility of developing them as new selective bioinsecticides.
基金National Natural Science Foundation of China and partly by the Grant-in-aid for Overseas Scientific Research from the Ministry of Education, Science and Culture, Japan.
文摘Scorpion anti-insect toxins can be divided into long chain (about 61-70 aminoacid residues)and short chain (about 5 amino acid residues) types according to theirmolecular size, and the former can be further divided into excitatory and depressanttypes on the basis of their pharmacological action. In our previous papers, the iso-lation and determination of the primary structure of an excitatory
基金Project supported by a grant from Youth Foundation (388008) to Ji Yong-hua from the National Natural Science Foundation of China and the grant-in-aid for overseas scientific research from the Ministry of Education,Science and Culture,Japan.
文摘Suitable pattern and high yield were obtained when the reverse-phase performance liquidchromatography (RP-HPLC) was used to separate neurotoxins from venom of Chinese scorpion Buthusmartensi Karsch.Using this technique,the venom was first separated to two main regions.The toxicitytests show that the insect-selective neurotoxical components are concentrated in the latter region,from whichfive insect-selective neurotoxins designated by BmK IT1-IT5 were obtained.According to the results of thetoxicity test as well as the amino acid composition and N-terminal analyses,BmK IT1 is the excitatory insectneurotoxin as reported in a previous paper,and the others are the newly found depressant insect-selectiveneurotoxins.The molecules of all the four toxins are single-chain minipeptides of about 60 amino acids.Their isoelectric points (pI) are between 8.3 and 8.5.The fact that BmK IT2 loses completely its insect tox-icity after being modified by fluorochrome shows that the positive charges on the molecular surface of thiskind of toxins are important to maintaining the bioactivity of the molecules.
