JACS--Aryl thiol substrate 3-carboxy-4-nitrobenzenethiol strongly stimulating thiol peroxidase activity of glutathione peroxidase mimic 2, 2 ''''''''-ditellurobis(2-deoxy-beta-cyclodextrin)
作者：Dong, ZY; Liu, JQ; Mao, SZ; et al.
關(guān)鍵字：Molecular Recognition, Catalysis, Glutathione Peroxidase, Cyclodextrin
論文來源：期刊
發(fā)表時間：2004年
Artificial glutathione peroxiclase (GPx) model 2, 2''''''''-ditellurobis(2-deoxy-beta-cycloclextrin) (2-TeCD) which has the desirable properties exhibited high substrate specificity and remarkably catalytic efficiency when 3-carboxy-4-nitrobenzenethiol (ArSH) was used as a preferential thiol substrate. The complexation of ArSH with P-cyclodextrin was investigated through UV spectral titrations, fluorescence spectroscopy, H-1 NMR and molecular simulation, and these results indicated that ArSH fits well to the size of the cavity of g-cyclodextrin. Furthermore, 2-TeCD was found to catalyze the reduction of cumene peroxide (CuOOH) by ArSH 200 000-fold more efficiently than diphenyl diselenide (PhSeSePh). Its steady-state kinetics was studied and the second rate constant k(max)/K-ArSH was found to be 1.05 x 10(7) M-1 min(-1) and similar to that of natural GPx. Moreover, the kinetic data revealed that the catalytic efficiency of 2-TeCD depended strongly upon the competitive recognition of both substrates for 2-TeCD. The catalytic mechanism of 2-TeCD catalysis agreed well with a ping-pong mechanism, in analogy with natural GPx, and might exert its thiol peroxiclase activity via tellurol, tellurenic acid, and tellurosulfide.