6-CySeCD的合成及催化作用

Synthesis of selenium-containing cyclodextrin as glutathione peroxidase mimics and its catalytic action

以β-环糊精为酶模型,合成了具有谷胱甘肽过氧化物酶(GPx)活性的抗氧化模拟物6A,6A′-环己胺基-6B,6B′-二硒桥联-β-环糊精(6-CySeCD).采用元素分析、红外光谱1、3CNMR和X光电子能谱进行了结构表征.该模拟物的稳态动力学表现出米氏动力学特征,其催化机制可能与天然酶遵循相同的乒乓机制,催化GSH还原H2O2的GPx活力为7.9U/μmol,比Ebselen(0.99 U/μmol)高7.9倍,比6-SeCD(4.2 U/μmol)高1.8倍,即环己胺定向引入增强了其活力.

On the basis of structural understanding for GPx, supromolecular host molecules, were selected cyclodextrins, as the scaffolds of enzyme models, and introduce catalytic sites Se and cyclohexyl- amine near the Se sites by chemical modification. One system of GPx mimic：cyclodextrin-based GPx models, 6A, 6B-cyclohexylamine-6Al, 6B′- selenium-bridged β-cyclodextrin （6-CySeCD） was obtained. The structure of the mimic was characterized by means of elemental analysis, IR and 13CMR and its selenium content and valence were determined by means of x-ray photoelectron spectra. Double recioro- cal plots of the inititial velocity versus the concentration of substrates were a family of parallel lines, consistent with a Ping-Pang mechanism involving at least one covalent enzyme intermediate. The GPx activity of the mimic for reduction of H2O2 by glutathione is 7.9 U/μmol,which is 7.9 times of that of ebselen. The GPx activity of the mimic for reduction of H2O2 by glutathione is 1.8 times of that 6- SeCD （4.2 U/μmol）. Detailed steady-state kinetic studies demonstrated that the 6-SeCD followed a ping-pong mechanism similar to the naturally occurring GPx. Cyclohexylamine near the Se sites by chemical modification rose the activity of the mimic.