Glutathione peroxidase GSHPx

The cytosolic compartment in mammalian cells is protected from oxidative damage caused by H2O2, by catalase and by the selenoenzyme glutathione peroxidase (GSHPx) GSHPx is also present in the mitochondria of all mammalian cells. 

The concentrations of selenium in whole blood and in plasma and/or serum are related to dietary intake. About 50% to 60% of the total plasma selenium is present as the protein selenoprotein P, a highly basic protein having multiple histidine residues and about 10 atoms of selenium per molecule, Around 30% of plasma selenium is present as glutathione peroxidase (GSHPx-3) and the remainder is incorporated into albumin as selenomethionine. ... 

Early animal studies and human population surveys used whole blood as the main indicator of selenium status. Whole blood selenium can be determined after acid digestion using a fluorometric method. The more convenient carbon furnace atomic absorption spectroscopy (CFAAS) assay for plasma and/or serum selenium is now the most widely used procedure. The main components of plasma selenium are extracellular glutathione peroxidase (GSHPx 3) and selenoprotein P. 

The enzymatic system includes enzymes, such as superoxide dismutase (SOD), glutathione peroxidase (GSHPx), catalase, and others. SOD catalyzes the dismutation of 02 at a rate constant 104 times higher than that for spontaneous dismutation at pH 7.4 (Eq. 1) [39]. 

There has been substantial attention given to the interactions between vitamin E and either selenium or vitamin C. The majority of work concerning selenium in meat-producing animals has dealt with animal disease rather than effects on quality of muscle foods. Selenium is part of the antioxidant enzyme, glutathione peroxidase (GSHPx). Yamauchi et al. (1984b) presented evidence for a compensational relationship between... 

GSHPx Glutathione peroxidase GSSG Glutathione (oxidized)... 

Values are mean SEM. LPO lipid peroxidation NOPs nitric oxide products SOD superoxide dismutase GSH reduced glutathione GSSG oxidized glutathione GR glutathione reductase GSHPx glutathione peroxidase MT metallothionein. p < 0.05 versus untreated control group. (Adapted from Ayaz and Turan, 2006.)... 

Red cell glutathione peroxidase activity (GSHPx-1) in adults varies from 13 to 25U/g Hb, whereas values in children are slightly lower. Local age-related reference intervals are again required. 

One way that selenium appears to act is as a non-specific stimulant of immune competent tissues and cells contributing to its anti-inflammatory, immunopotentiation and carcinostatic attributes. Additional data suggests other effects of Se upon cells of the immune system perhaps independent of GSHPx activity such as ubiquinone biosynthesis, (Coenz3one Q 10) which in turn affects host-defense mechanisms (Frost, 1975). A third possibility to explain the effects attributed to Se above is to propose that increases in levels of the selenium dependent enzyme glutathione peroxidase and perhaps other specific selenium-dependent functions in lymphocytes and macrophages is the reason for immunoenhancement. This subject has been addressed by Schauzer (1979) and is amplified here by the author. 

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