谷胱甘肽过氧化物酶模拟物2-位碲桥联环糊精的合成及催化作用  

Synthesis of 2-Tellurium Bridged Cyclodextrin as Glutathione Peroxidase Mimics and Its Catalytic Action

作　　者：张鲲[1] 任晓君[1] 牟颖[1] 薛雁[1] 郭灿辉[1] 阎岗林[1] 罗贵民[1] 沈家骢[2] 

机构地区：[1]吉林大学分子酶学工程教育部重点实验室,吉林长春130023 [2]吉林大学超分子结构与材料教育部重点实验室,吉林长春130023

出　　处：《催化学报》2003年第2期97-102,共6页

基　　金：国家 973计划资助项目 (G2 0 0 0 0 7810 0 );国家自然科学基金资助项目 ( 2 0 0 72 0 10 ;2 0 2 72 0 16)

摘　　要：以 β 环糊精 (CD)为酶模型 ,将Te引入 β 环糊精中 ,成功地合成出一种新的水溶性好、活力高的谷胱甘肽过氧化物酶(GPX)小分子模拟物 2 TeCD ,并对其结构进行了表征 .采用Wilson辅酶偶联法 ,间接测定了 2 TeCD催化还原型谷胱甘肽(GSH)还原H2 O2 的GPX活力为 46 7U/ μmol,与文献报道的数据相比 ,2 TeCD的GPX活力最高 .通过考察 2 TeCD催化GSH还原H2 O2 反应的动力学 ,发现反应初速度对底物浓度的双倒数曲线为一组平行线 ,表明 2 TeCD所遵循的催化机制可能为三转移乒乓机制 .通过考察自由基捕获剂 2 ,4 二叔丁基甲基苯酚对酶促和自发反应速率的影响 ,发现 2 TeCD催化的酶促反应为非自由基机理 .通过考察酶不可逆抑制剂碘乙酸对酶促反应速率的影响 ,发现 2 TeCD催化反应过程中不生成碲醇中间体 .由此推测出 2 TeCD的催化循环经历碲硫化合物、次碲酸硫酯和次碲酸中间体 .该催化循环与含硒GPX小分子模拟物所经历的催化循环不同 ,以及环糊精对底物具有识别与结合的能力 ,可能是 2Glutathione peroxidase (GPX) is a mammalian selenoenzyme that can catalyze reduction of hydroperoxides by glutathione (GSH). Because of some limitations in gaining and applying GPX, considerable efforts have been made to find compounds that could mimic GPX. A novel dicyclodextrinyl ditelluride compound, 2-tellurium bridged β-cyclodextrin (2-TeCD), was synthesized, and exhibited good water solubility and high GPX activity. The GPX activity of 2-TeCD for reduction of H_2O_2 by GSH is 46.7 U/μmol, being the highest among the small molecular GPX mimics. The kinetic study for enzymatic peroxidase reaction was undertaken at all the individual concentration of GSH and H_2O_2, and the double-reciprocal plots of initial rate vs substrate concentration were a family of parallel lines, indicating that the mechanism of the 2-TeCD-catalyzed reduction is a ping-pong mechanism. The 2-TeCD-catalyzed reduction does not involve the radical reaction, while the spontaneous reaction involves it. The CDTeH was not involved in the 2-TeCD-catalyzed reduction. So it was presumed that the process of 2-TeCD-catalyzed reduction includes three intermediates, which was different from those of selenide compounds.

关 键 词：谷胱甘肽过氧化酶 2-位碲桥联环糊精 合成 催化作用 人工酶 

分 类 号：O643.3[理学—物理化学]