分泌癌胚抗原肿瘤靶向性Cu,Zn-SOD的基因克隆及表达

将Cu，Zn-SOD与抗癌胚抗原（CEA）单链抗体基因（ScFvgene)融合，重组到含T7启动子的表达载体p ET-22b(＋）中，构建表达质粒pETSOD－ScFv，并转化大肠杆菌BL21（ED3），进行了高效表达，表达物占菌体可溶性总蛋白的18％。SDS－PAGE和蛋白质印迹图谱显示表达物相对分子质量为41kD，与融合基因编码蛋白质的理论值相符。该蛋白质在磊肠杆菌中为分泌型表达，有利于纯化。RIA测定表明产物能特异性地与抗原CEA结合，邻苯三酚法测定也表明产物具有SOD酶的活性，该融合蛋白为分泌CEA肿瘤的靶向性治疗及放疗、化疗后的恢复提供新的途径。

Cloning and Expression of Targeting Human Cu, Zn-SOD to Tumors Which Can Secret CEA in E.coli

The gene encoding human Cu,Zn SOD was fused to anti carcinoembryonic antigen single chain antibody gene to construct the fusion gene, then was ligated into prokaryotic expression vector pET 22b(+). The fusion gene was expressed in E.coli at high level, and was characterized by SDS PAGE and Western blot analysis. The expression product which accounting for 18% of the total bacteria protein had the CEA binding ability in RIA, and also had the SOD activity by pyrogallol autoxidition assay. So, the Cu,Zn SOD moiety retains substantial enzymatic activity, where the ScFv moiety can delivers the fusion protein to tumor. Cu,Zn SOD is a potential tumor relevant gene, maybe the fusion protein can provide a new pathway to therapy tumors and to meet the damage after radiation or chemical therapy.