Aryl thiol substrate 3-carboxy-4-nitrobenzenethiol strongly stimulating thiol peroxidase activity of glutathione peroxidase mimic 2, 2'-ditellurobis(2-deoxy-beta-cyclodextrin).
Artificial glutathione peroxidase (GPx) model 2, 2'-ditellurobis(2-deoxy-beta-cyclodextrin) (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 beta-cyclodextrin was investigated through UV spectral titrations, fluorescence spectroscopy, 1H NMR and molecular simulation, and these results indicated that ArSH fits well to the size of the cavity of beta-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 kmax/KArSH 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 peroxidase activity via tellurol, tellurenic acid, and tellurosulfide.
Dong
Zeyuan
Z
Key Laboratory for Supramolecular Structure and Materials of Ministry of Education, Jilin University, Changchun 130012, Peoples Republic of China.
Liu
Junqiu
J
Mao
Shizhong
S
Huang
Xin
X
Yang
Bing
B
Ren
Xiaojun
X
Luo
Guimin
G
Shen
Jiacong
J
D001555:Benzene Derivatives / Q000737:chemistry / Q000378:metabolism; D040761:Biomimetic Materials / Q000737:chemistry* / Q000378:metabolism; D002384:Catalysis; D003505:Cyclodextrins / Q000737:chemistry* / Q000378:metabolism; D005978:Glutathione / Q000737:chemistry / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000737:chemistry* / Q000378:metabolism; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000737:chemistry* / Q000378:metabolism; D016566:Organoselenium Compounds / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013379:Substrate Specificity; D013438:Sulfhydryl Compounds / Q000737:chemistry* / Q000378:metabolism; D013691:Tellurium / Q000737:chemistry / Q000378:metabolism
D001555:Benzene Derivatives; D003505:Cyclodextrins; D009942:Organometallic Compounds; D016566:Organoselenium Compounds; D013438:Sulfhydryl Compounds; C442326:dicyclodextrinyl ditelluride; C061132:diphenyldiselenide; D005979:Glutathione Peroxidase; D005978:Glutathione; D013691:Tellurium; C093688:3-carboxy-4-nitrobenzenethiol