6A,6A'-苯胺-6B,6B'-硒桥联-β-CD底物的特异性

Substrate Specificity of 6A,6A'-Dianilino-6B,6B'-diselenide-bis-β-cyclodextrin

运用双酶偶联体系分别测定6A,6A'-二苯胺-6B,6B'-二硒桥联-β-CD(6-AnSeCD)催化谷胱甘肽(GSH)还原过氧化氢(H2O2)、叔丁基过氧化氢(t-BuOOH)和枯烯过氧化氢(CumOOH)3种结构不同氢过氧化物的谷胱甘肽过氧化物酶(GPx)活力,并考察6-AnSeCD催化这3种氢过氧化物的稳态动力学.结果表明:6-AnSeCD还原CumOOH的GPx活力最高;6-AnSeCD的催化机制为乒乓机制;6-AnSeCD的假一级反应速度常数(k max)、米氏常数(K m)和二级反应速率常数(k)均显示CumOOH为6-AnSeCD的最适底物.

The gluathione peroxidase （GPx） activities of 6A, 6A＇-dianilino-6B, 6B＇-diselenide-bis β- cyclodextrin （6-AnSeCD） in the reduction of H202, tert-butyl hydroperoxide （t-BuOOH） and cumenyl hydroperoxide （CumOOH） by glutathione （GSH） were assessed in classical coupled reductase assay, and the steady-state kinetics of 6-AnSeCD in the reduction of three hydrogen peroxides was studied. The 6-AnSeCD displayed best GPx activity for the reduction of CumOOH by GSH. A ping-pong mechanism was observed in the steady-state kinetic studies on the 6-AnSeCD- catalyzed reactions. We further compared kmax, Km and second-order rate constant of 6-AnSeCD. The results show the CumOOH is the most preferred substrate for 6-AnSeCD.