Summary:
Selenium is an essential trace element for animals. It is biologically active as selenocysteine in the active centre
of selenoproteins with enzymatic functions. Incorporation of selenocysteine occurs on the basis of genetic expression
and selenium is the only trace element under direct genetic control. Selenocysteine can be considered the 21st amino
acid with regard to its biosynthesis and incorporation into proteins. At least two types of selenoproteins are necessary
for each animal cell, the first from the family of GSH-peroxidases and the second from the family of deiodinases.
GSH-peroxidases are the most powerful antioxidant enzymes, which defend the cell and whole organism against
oxidative damage and thus from oxidative diseases and disorders such as cardiovascular diseases, malignancies,
bacterial or viral diseases, muscle dystrophy, arthropathy, arterial plaques, and others. GSH-Px have many other
regulatory functions such as regulation of biosynthesis of prostaglandins, prostacycline, leukotrienes, and thrombo-
xans. Deiodinases regulate the metabolism of biologically active triiodothyronine and thus thyroid hormone
regulation of the whole organism. Selenoproteins act against cancerogenic effects of some organic molecules and
bind heavy metals. Tissue-specific selenoproteins without a known biological function have been detectes in some
specialised tissues with a high priority for selenium. One of the regulators of selenoprotein synthesis is the selenium
status of the organism. Its state and intake may be assessed by analyses of selenium indexes. The most often used
indexes are serum selenium and urinary selenium. On the basis of its analyses in six regions of the Czech Republic,
severe selenium deficiency has been found in inhabitants of this country, which is even profound for more distressed
groups like growing children, pregnant and lactating women, and the elderly.
Key words:
selenium, selenoprotein, GSH-peroxidase, deiodinase, selenium deficiency in CR.
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