Functional mimicry of the active site of glutathione peroxidase by glutathione imprinted selenium-containing protein.

For imitating the active site of antioxidant selenoenzyme glutathione peroxidase (GPx), an artificial enzyme selenosubtilisin was employed as a scaffold for reconstructing substrate glutathione (GSH) specific binding sites by a bioimprinting strategy. GSH was first covalently linked to selenosubtilisin to form a covalent complex GSH-selenosubtilisin through a Se-S bond, then the GSH molecule was used as a template to cast a complementary binding site for substrate GSH recognition. The bioimprinting procedure consists of unfolding the conformation of selenosubtilisin and fixing the new conformation of the complex GSH-selenosubtilisin.

Cyclodextrin-derived mimic of glutathione peroxidase exhibiting enzymatic specificity and high catalytic efficiency.

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-beta-cyclodextrin) (2-TeCD) in the presence of a variety of structurally distinct hydroperoxides (ROOH), H2O2, tert-butyl peroxide (tBuOOH), 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.