Metabolism of selenium

Tuve, T. and Williams, H.H. 1961. Metabolism of selenium by Escherichia coli biosynthesis of selenomethionine. J. Biol. Chem. 236, 597-601. 

Shrift, A., 1973. Metabolism of selenium by plants and microorganisms. In D.L. Klayman and W.H.H. Gunther (Editors), Organic Selenium Compounds Their Chemistry and Biology. Wiley-Interscience, New York, NY, pp. 763—814. 

Selenate apparently is not converted to dimethyl selenide as readily as is selenite. Studies of selenate metabolism are limited in mammals, but studies using bacteria indicate that selenate must be activated prior to conversion to selenite (Bopp et al. 1982). Dilworth and Bandurski (1977) demonstrated that in the presence of ATP, magnesium (II) salts, and ATP-sulfurylase, yeast could convert selenate to eventually yield selenite (Figure 3-6). Data regarding the metabolism of selenium sulfide after administration to humans or other animals were not located in the literature. 

The metabolism of selenium is now fairly well understood. To become incorporated into selenium-specific proteins (e.g., glutathione peroxidase, thioredoxin reductase, iodothyronine 5 -deiodinase) through a cotranslational mechanism requires that selenium be in the form of selenide (Sunde 1990). All forms of selenium can be transformed to selenide, although the rates of transformation vary. For example, selenate is not converted to selenide as readily as selenite. The formation of selenide from selenocysteine requires a specific enzyme, selenocysteine (3-lyase, which catalyzes the decomposition of selenocysteine to alanine and hydrogen selenide. Excess selenium is methylated and exhaled or excreted in the urine in both humans and animals. Further research is required to determine which selenium metabolites or intermediates lead to toxicity. 

Wendel A, Otter R. 1987. Alterations in the intermediary metabolism of selenium-deficient mice. Biochim Biophys Acta 925 94-100. 

Selenocysteine lyase (SCL) from higher eukaryotes is the mammalian counterpart to bacterial enzymes and is thought to play a vital role in the metabolism of selenium in the cell. " SCL has been shown to be similar in amino acid composition to the NifS family, thus suggesting a similar mechanism used to generate elemental... 

R650 Y. Ogra, Metabolisms of Selenium and Tellurium in Plants , Biomedical Research on Trace Elements, 2009, 20, 240. 

Suzuki, K.T., Shiobara,Y, Ishiwata, K., and Ohmichi, M. (1997). Speciation by HPLC/ICP-MS with use of stable isotopes Chemical reactions in the metabolism of selenium administered as selenite.J. Inorg. Biochem. 67(1—4), 21. 

Whanger PD (1998) Metabolism of selenium in humans. Journal of Trace Elements and Experimental Medicine 11 227-240. 

Self WT, TC Stadman (2000) Selenium-dependent metabolism of purines a selenium-dependent purine hydroxylase and xanthine dehydrogenase were purified from Clostridium purinolyticum and characterized. Proc Natl Acad Sci USA 97 7208-7213. 

Hu, M.-L., Dillard, C.J. and Tappel, A.L. (1988) Aurofhioglucose effect on sulfhydryls and glutathione-metabolizing enzymes in vivo inhibition of selenium-dependent glutathione peroxidase. Research Communications in Chemical Pathology and Pharmacology, 59,... 

Guyan et al. 1990) have used several markers of lipid peroxidation (9-cis-, 11-tmns-isomer of linoleic acid, conjugated dienes and ultraviolet fluorescent products) to demonstrate significant increases in the duodenal aspirate after secretin stimulation in patients with acute and clinic pancreatitis. They interpreted this as indicating induction of hepatic and pancreatic drug-metabolizing enzymes in the face of a shortfidl of antioxidant defences, more marked in chronic pancreatitis. Subsequent studies in patients with chronic pancreatitis have confirmed decreased serum concentrations of selenium, -carotene and vitamin E compared with healthy controls (Uden et al., 1992). Basso aol. (1990) have measured increases in lipid peroxides in the sera of patients with chronic... 

Whanger PD, Ip C, Polan CE, Uden PC and Welbaum G. 2000. Tumorigenesis, metabolism, speciation, bioavailability, and tissue deposition of selenium in selenium-enriched ramps (Allium tricoccum). J Agric Food Chem 48(11) 5723-5730. 

Metabolism and degradation of selenium are both significantly modified by interaction with various heavy metals, agricultural chemicals, microorganisms, and numerous physicochemical factors and until these interactions are resolved, it will be difficult to meaningfully interpret selenium residues... 

Lemly, A.D. 1993c. Metabolic stress during winter increases the toxicity of selenium to fish. Aquat. Toxicol. 27 133-158. 

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