眼镜蛇血清解毒蛋白的溴化氰裂解肽段与自身神经毒素的结合

Toxin-binding Activity of Cyanogen Bromide Cleaved Peptide Fragments of the Chinese-cobra Serum Antitoxic Protein

目的为进一步认识眼镜蛇血清解毒蛋白（ＣＳＡＰ）如何与神经毒素结合并解毒。方法用溴化氰裂解ＣＳＡＰ肽链中由Ｍｅｔ羧基端组成的肽键，裂解产物经超滤除去分子量小于１００００的片段后，用亲和层析法得到与毒素仍保持有亲和力的肽段。结果与毒素仍保持有亲和力的肽段相当于Ｌｙｓ２－Ｍｅｔ４８５，Ｌｙｓ２－Ｍｅｔ２７５，Ｌｙｓ２７６－Ｍｅｔ４８５，Ｐｒｏ４４４－Ｍｅｔ６０３。结论ＣＳＡＰ的３个结构域均具有与毒素分子结合的活性，ＣＳＡＰ结合的８个毒素分子分散在整个肽链的各个段落上。

For further study of the structure-function relationship of the Chinese cobraserum antitokic protein. Methods Cyanogen bromide was used to cleave the peptide bondswhich formed by the carboxyl group of Met residues. The cleaved products were ultrafiltrated toremove the small fragments below 10 000 and P8ssed an affinity column packed with Sepharose4B linked with cobrotoxin as ligand. The molecular weight and N-terminal amino acid residues ofthe cleaved peptide fragments bounded to the affinity column were then assayed. Results Thecleaved peptide fragments reserved toxin-binding activity were proved to be Lys2-Met485, Lys2Met275, Lys276-Met485, Pro444-Met603. Conclutions This result reveavied that all thethree domains of CSAP, along the peptide chain, possess the toxin binding activity.