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Cyclodextrin‐Derived Mimic of Glutathione Peroxidase Exhibiting Enzymatic Specificity and High Catalytic Efficiency
Author(s) -
Dong ZeYuan,
Huang Xin,
Mao ShiZhong,
Liang Kai,
Liu JunQiu,
Luo GuiMin,
Shen JiaCong
Publication year - 2006
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200501098
Subject(s) - chemistry , diphenyl diselenide , thiol , ebselen , peroxide , glutathione , peroxidase , substrate (aquarium) , cyclodextrin , glutathione peroxidase , cumene hydroperoxide , moiety , stereochemistry , catalysis , enzyme , combinatorial chemistry , biochemistry , organic chemistry , oceanography , selenium , geology
To elucidate the relationships between molecular recognition and catalytic ability, we chose three assay systems using three different thiol substrates, glutathione (GSH), 3‐carboxyl‐4‐nitrobenzenethiol (CNBSH), and 4‐nitrobenzenethiol (NBSH), to investigate the glutathione peroxidase (GPx) activities of 2,2′‐ditellurobis(2‐deoxy‐β‐cyclodextrin) (2‐TeCD) in the presence of a variety of structurally distinct hydroperoxides (ROOH), H 2 O 2 , tert ‐butyl peroxide ( t BuOOH), and cumene peroxide (CuOOH), as the oxidative reagent. A comparative study of the three assay systems revealed that the cyclodextrin moiety of the GPx mimic 2‐TeCD endows the molecule with selectivity for ROOH and thiol substrates, and hydrophobic interactions are the most important driving forces in 2‐TeCD complexation. Furthermore, in the novel NBSH assay system, 2‐TeCD can catalyze the reduction of ROOH about 3.4×10 5 times more efficiently than diphenyl diselenide (PhSeSePh), and its second‐order rate constants for thiol are similar to some of those of native GPx. This comparative study confirms that efficient binding of the substrate is essential for the catalytic ability of the GPx mimic, and that NBSH is the preferred thiol substrate of 2‐TeCD among the chosen thiol substrates. Importantly, the proposed mode of action of 2‐TeCD imitates the role played by several possible noncovalent interactions between enzymes and substrates in influencing catalysis and binding.