Glutathione Peroxidase GPX

The present chapter reviews applications in biocatalysis of the ONIOM method. The focus is on studies performed in our research group, in most cases using the two-layer ONIOM(QM MM) approach as implemented in Gaussian [23], The studied systems include methane monooxygenase (MMO), ribonucleotide reductase (RNR) [24, 25], isopenicillin N synthase (IPNS) [26], mammalian Glutathione peroxidase (GPx) [27,28], Bi2-dependent methylmalonyl-CoA mutase [29] and PLP-dependent P-lyase [30], These systems will be described in more detail in the following sections. ONIOM applications to enzymatic systems performed by other research groups will be only briefly described. 

Glutathione peroxidase (GPx) Activity significantly increased by some concentrations > 6.1 mgL Activity not affected Activity not affected Activity not affected... 

Effect of standardized P. ginseng extract G115 after exhaustion exercise glutathion peroxidase (GPX) enzymatic activity (red gastrocnemius) "mitochondrial fraction."... 

To reduce the injurious effect of oxidative stress, cells are equipped with two major antioxidant defense systems. The first concerns numerous enzymes, which catalyze ROS degradation, such as superoxide dismutase (SOD), catalase or glutathione peroxidase (GPx) ... 

Because free radicals are necessary for life, the human body has a number of mechanisms to minimize free-radical-induced damage and to repair the damage that does occur, such as the primary enzymes superoxide dismu-tase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione... 

Devasena and Menon (2007) reported that fenugreek seeds had a modulatory effect on colon tumour incidence, as well as hepatic lipid peroxidation (LPO) during DMH (1,2-dimethylhydrazine) colon carcinogenesis in male Wistar rats. In DMH-treated rats, 100% colon tumour incidence was accompanied by enhanced LPO and a decrease in reduced glutathione (GSH) content, as well as a fall in glutathione peroxidase (GPx), glutathione S-transferase (GST), superoxide dismutase (SOD) and catalase (CAT) activities. Inclusion of fenugreek seed powder in the diet of DMH-treated rats reduced the colon tumour incidence to 16.6%, decreased the lipid peroxidation and increased the activities of GPx, GST, SOD and CAT in the liver. 

Selenium is an essential trace element, being important in at least two critical enzymes, the antioxidant glutathione peroxidase (GPx), and type 1 iodothyronine deiodinase. GPx converts hydrogen peroxide to water, in the presence of reduced glutathione, while iodothyronine deiodinase catalyzes the conversion of thyroxine to triiodothyronine, the physiologically active hormone species. 

---