梭曼单链抗体酶EP_6一级结构的确定和三维结构的模建

Establishmentof primary structure and modeling of three dimen- sionalstructure of anti-soman single-chain catalytic antibody EP6

以梭曼水解反应过渡态类似物 O1-甲基 - O2 -(1 ,2 ,2 -三甲基丙基 ) - 2 -羟基 - 5-硝基苯基甲基膦酸为半抗原得到了梭曼单链抗体酶 EP6.对这一株抗体进行了核苷酸序列的测定 ,测序结果表明这一单链抗体基因全长 71 4bp,其中重链长 351 bp,编码1 1 7个氨基酸 ,轻链长 31 8bp,编码 1 0 6个氨基酸 ,二者由编码 (Gly4 Ser) 3的 45bp的连接肽基因相连 .重 ,轻链均为开放读框 ,有明确的四个框架区和三个互补决定区 (CDR)以及抗体特征性的两个半胱氨酸残基 ,表明重 ,轻链的氨基酸序列符合鼠抗体可变区特征 .在 SGI工作站上对 EP6的三维结构进行了同源模建 .计算机模型显示 EP6表面包含一个由重轻链 CDRs围成的 ,可能用于半抗原结合和催化活性的长裂缝 ,其中轻链的 CDR3(L- CDR3)和重链三个 CDRs(H- CDRs)都可能参与抗原或半抗原的接触 ,L- CDR3和 H- CDR2的贡献较大 。

A single- chain catalytic antibody (Sc Fv) EP6 using O1 - methyl- O2 - (1 ,2 ,2 - trimethylpropyl ) - 2 - hydroxy- 5 - nitrophenyl methylphosphonic acid as hapten has been reported recently.In this paper,the gene of Sc Fv EP6 was analyzed and the amino acid sequence was deduced.The results show that VH and VL gene are homologous with the published mouse antibody variable re- gion gene sequences.The VH and VL genes are 35 1 bp and 31 8bp respectively and both of them are capable of encoding 1 1 7and 1 0 6 amino acids.The deduced amino acid se- quences contain four FRs,three CDRs and two cysteine residues necessary for the maintenance of the antibody structure,indi- cate that they are functionally rearranged. The three dimensional structure of EP6 was also modeled by computer homology model- ing techniques. The preliminary results show that the binding region of EP6is com- posed of CDR3of the lightchain and CDR1 , CDR2 and CDR3of the heavy chain.