In this communication, we report the synthesis of the three generations of Fre

A strategy for design of bioimprinted proteins with glutathione peroxidase (GPX) activity has been proposed. The proteins imprinted with a glutathione derivative were converted into selenium-containing proteins by chemical modifying the reactive hydroxyl groups of serines followed by sodium hydrogen selenide displacement. These selenium-containing proteins exhibited remarkable GPX activities and the GPX activities of reduction of H2O2 by glutathione (GSH) were found to be 101-817U mol−1, which approaches the activity of a selenium-containing catalytic antibody elicited by a hapten similar to our template. The steady state kinetic study for imprinted protein catalysis revealed Michaelis–Menten kinetics for both H2O2 and GSH, e.g. the pesudo-first-order rate constant kcat (H2O2) and the apparent Michaelis constant Km (H2O2) at 1mM GSH were calculated to be 784min−1 and 1.24×10−3 M, respectively, and the apparent second-order rate constant kcat (H2O2)/Km (H2O2) was determined to be 6.33×105 (M min)−1. The kinetics and the template inhibition showed that the strategy might be a remarkably efficient one for generating artificial enzyme with GPX activity.

A novel dicyclodextriyl ditelluride (2-TeCD) compound was devised as a functional mimic of the glutathione peroxides (GPX) enzymes that nomally remove hydroperoxides from the cell. The GPX activity of the mimic was found to be 46.7U

Glutathione peroxidase (GPX) protects cells against oxidative damage by catalyzing the reduction of hydro-peroxides by glutathione (GSH). GPX therefore has potential therapeutic value as an antioxidant, but its pharmacological development has been limited be-cause GPX uses a selenocysteine as its catalytic group and it is difficult to generate selenium-containing pro-teins with traditional recombinant DNA technology. Here, we show that naturally occurring proteins can be modified to generate GPX activity. The rat theta-thiclass glutathione transferase T2-2 (rGST T2-2) pre-sents an ideal scaffold for the design of a novel GPX catalyst because it already binds GSH and contains a natuserine close to the substrate binding site, which can engibe chemically modified to bind selenium. The modified Se-rGST T2-2 efficiently catalyzes the reduction of hy-drogen peroxide, and the GPX activity surpasses the activities of some natural GPXs.

Mimicking of natural enzyme systems with catalytically active arrangements in designed receptors is a challenging topic for chemists. Notable achievements to date have been obtained with several model systems, such as synthetic macrocyclic compounds, molecular assemblies, catalytic antibodies, and molecularly imprinted polymers.[1] Among these models, molecular imprinting has been demonstrated to be an attractive strategy for creating catalytically active binding sites for enzyme mimetics.[2] This method should give the opportunity to generate more complicated active sites with a high similarity to natural systems. For this purpose, to mimic enzyme behavior, especially esterase activity, numerous experiments have been undertaken by imprinting with transition-state analogues (TSAs).[3, 4] Although the earlier attempts to mimic enzyme behavior using imprinted polymers showed only limited catalytic efficiency, significant rate enhancement by catalysis with imprinted polymers has been obtained in recent years.[4] Evidently, increasing the transition-state binding, as well as correctly incorporating and positioning the functional groups is essential for the construction of an effective enzyme model.[1–4] In our previous work on preparing polymer catalysts by molecular imprinting,[4] amidinium functional groups were oriented in imprinted cavities. These groups acted as anchors for binding the tetrahedral transition states of basic ester or carbonate hydrolysis in a similar manner to the catalytic role of guanidinium moieties in certain catalytic antibodies [1c] and in carboxypeptidase A.[5] The catalytic action of carboxypeptidase Ainvolves two guanidinium groups and a Zn2+ ion. The guanidinium moiety of Arg127 binds the oxyanion generated in the rate-limiting formation of the tetrahedral transition