Superoxide dismutase selenium

Bebien M, G Lagniel, J Garin, D Touati, A Vermeglio, J Labarre (2002) Involvement of superoxide dismutases in the response of Escherichia coli to selenium oxides. J Bacterial 184 1556-1564. 

To prevent membrane damage, the red cell has an armoury of antioxidants, notably a manganese or selenium containing enzyme called superoxide dismutase (SOD) and the sulfydryl compound glutathione (GSH), a tripeptide of y-glutamate, cysteine and glycine. 

Glutathione peroxidase is a selenium enzyme and the reason that selenium is required in the diet. H2Oz most often comes from the superoxide anion (02 ) by the action of superoxide dismutase, which is generated when hemoglobin is oxidized to methemoglobin ... 

Zhu, J.-H., and Lei, X. G. Double null of selenium-glutathione peroxidase-1 and copper,zinc-superoxide dismutase enhances resistance of mouse primary hepatocytes to acetaminophen toxicity. Exp. Biol. Med. 231 545-552, 2006. 

The intercepting defenses scavenge the generated free radicals. As mentioned previously, superoxide dismutase and a-tocopherol are good examples of enzyme and nonenzyme scavengers, respectively. Some dietary minerals are essential for the function of antioxidant enzymes (e.g., the various isoforms of superoxide dismutase use copper and zinc or manganese as cofactors, whereas an isoform of glutathione peroxidase uses selenium). 

It may be of interest to know that the most efficient peroxidase contains selenium and is the reason why selenium is a necessary trace element. The most efficient superoxide dismutase in eukariotic cells contains copper. Copper is thus an important element for protection against free radicals but is also responsible for their formation. Copper ions form very stable SH compounds and would have been toxic without being superoxide generators. 

Figure 51.1 Antioxidant enzyme activities and LP levels in thyroid tissues of iodine- and selenium-deficient rats. Source Giray ef a/., 2004, with kind permission from Wiley-Liss. Superscripts of different letters differ significantly Ip < 0.05) from each other. Abbreviations C, control group ID, iodine-deficient group SeD, selenium-deficient group cGPx, glutathione peroxidase SOD, superoxide dismutase CAT, catalase TEARS, thiobarbituric acid reactive substances LP, lipid peroxidation.

Zinc deficiency places an increased demand on selenium (Se) pools in daphnids. As little as 5.0 p,g Se/L in zinc-free water eliminated overt cuticle damage and substantially increased reproduction, but did not alter the shortened life span. Cladocerans at the threshold of selenium deficiency will become overtly selenium-deficient when zinc supplies are lacking. Insufficient copper introduces cuticle problems in daphnids similar to those introduced by insufficient zinc or selenium, increasing the likelihood of a proposed relation between glutathione peroxidase (which contains selenium), and copper-zinc superoxide dismutase. High levels of dietary tin increased zinc loss from rats. Zinc prevented toxic effects of vanadium (lO.Omg/kg BW) on bone metabolism of weanling rats. 

Figure 13.1. Oxidant - antioxidant balance. O, reactive oxygen species AA, arachidonic acid SOD, superoxide dismutase Me, metals Se, selenium.

When rats are administered with bacoside A (10 mg/kg), levels of glutathimie, vitamin C, vitamin E, and vitamin A were reduced. The activities of superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase were also assayed. Copper, iron, zinc, and selenium levels in brain and serum ceruloplasntin activity were also measured. Administration of bacoside A improved the antioxidant status and maintained the levels of trace elements [16]. 

Susceptibility factors Renal disease Plasma copper, selenium, and zinc concentrations and antioxidant metalloenzymes, glutathione peroxidase (GPX) and superoxide dismutase (SOD), were studied in 17 patients on maintenance hemodialysis, 14 uremic patients, and 14 healthy subjects [46 ]. Plasma selenium concentrations and erythrocyte GPX were significantly lower in those on hemodialysis, and the two were correlated. There was also a correlation between reduced plasma zinc and erythrocyte SOD activity. 

Serfass, R. E. and Ganther, H. E. (1976) Effects of dietary selenium and tocopherol on glutathione peroxidase and superoxide dismutase activities in rat phagocytes. Life Sciences 19 1139-1144. 

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