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制备抗癌胚抗原 (CEA )单克隆抗体的单链抗体 ,在保留抗原抗体结合位点的同时有效降低抗体的分子量不仅可减少人抗鼠抗体反应 (HAMA ) ,而且适合放射免疫显像。为纯化及核素标记抗体 ,将单链抗体基因与核心链霉亲和素基因融合并在大肠杆菌得到高效表达 ,表达量占菌体总蛋白的 2 4%。SDS PAGE和蛋白质印迹图谱显示表达产物分子量为 41kD ,与其基因编码蛋白质的理论推算值相符。表明融合蛋白能特异性地与生物素结合 ,RIA表明表达产物具有结合其特异性抗原CEA的能力 ,以HRP标记的生物素作为抗体进行蛋白质印迹在 41kD处可见表达条带。说明表达物不仅能与生物素结合且能特异性地与CEA结合。
The preparation of a single-chain antibody against a monoclonal antibody against CEA (monoclonal antibody) can effectively reduce the molecular weight of the antibody while retaining the antigen-antibody binding site. This not only reduces human anti-mouse antibody response (HAMA) but also is suitable for radioimmunoimaging. To purify and label the antibody, the single-chain antibody gene was fused to the core streptavidin gene and expressed highly in E. coli, which accounted for 24% of the total bacterial protein. SDS PAGE and Western blotting showed that the expressed product had a molecular weight of 41 kD, which was in accordance with the theoretically estimated value of the protein encoded by the gene. The fusion protein showed specific binding to biotin. RIA showed that the expressed product had the ability to bind its specific antigen CEA. HRP-labeled biotin was used as an antibody for Western blotting and the expression band was observed at 41 kD. This indicates that the expression product binds not only biotin but also specifically binds to CEA.