一种催化甲状腺素脱碘的抗体酶

AN ABZYME TO CATALYTIZE THE DEIODINATION OF THYROXINE

目的 模拟生物体内一族重要的含硒酶 甲状腺素脱碘酶 ,制备催化甲状腺素脱碘的含硒抗体酶。方法用杂交瘤技术制备出抗甲状腺素的单克隆抗体 4C5 ,再用化学修饰法将催化基团硒代半胱氨酸引入到抗体的抗原结合部位 ,得到含硒抗体酶Se 4C5 ;通过RIA方法测定抗体酶活力。结果 抗体酶Se 4C5有明显的催化甲状腺素脱碘活性 ,其Vmax为 2 70pmol·min- 1 ·mg- 1 (protein) ;催化反应速率与底物浓度的双倒数图为一组平行线 ;对底物甲状腺素的特异性高于天然酶 ;6 丙基 2 硫代尿嘧啶对其活力起抑制作用 ,是二硫苏糖醇 (DTT)的竞争性抑制剂。结论 首次制备出有天然脱碘酶活性的抗体酶 。

AIM To mimic an important family of selenoenzymes in organism thyroxine (T 4) deiodinases and prepare a selenium containing abzyme catalyzing deiodination of T 4. METHODS A anti T 4 monoclonal antibody was generated by hybridoma methodology and converted into a selenium containing abzyme by the method of chemical modification. The catalytic activity of the enzyme was measured by RIA method. RESULTS The abzyme displayed a marked activity of catalyzing deiodination of T 4 and a higher specificity to the substrate T 4 than that of natural enzyme, and the double reciprocal plots of the initial rates of T 3 formation vs. T 4 concentration yielded a family of parallel lines. The catalytic activity could be sensitively inhibited by 6 propyl 2 thiouracil (PTU), a competitive inhibitor for dithiothreitol (DTT). CONCLUSION An abzyme with the diodination activity was first prepared and the reaction mechanism of the enzyme was bisubstrate ping pong one.