ABSTRACT

Selenium was named and identied by Jons Jacob Berzelius in 1817 during the study of sulfuric production [1]. In the rst 125 years since the discovery, this element was considered toxic to farm animals or as a drug to shrink tumors. The proposed chronic selenium toxicity, known as “alkali disease” or “change hoof disease,” observed in farm animals was rst experimentally veried in 1934 by Kurt Franke, who observed that rats fed seleniferous plants grown on the lands rich in selenium

10.1 Early History: From Selenium to Selenoproteins ......................................... 273 10.2 Physiological Roles of Selenium and Selenoproteins ................................... 276

10.2.1 Selenoproteins ................................................................................... 276 10.2.1.1 The Selenium-Dependent Glutathione Peroxidase Family ... 277 10.2.1.2 Selenoproteins Involved in Thioredoxin (Trx) Signaling .... 279 10.2.1.3 Selenoproteins Involved in Thyroid Hormone Metabolism ...280 10.2.1.4 Selenoproteins Involved in Se Transportation and Storage... 281 10.2.1.5 Other Notable Selenoproteins ............................................ 281

10.2.2 Selenium Metabolites ....................................................................... 282 10.3 Epigenetic Regulation by Selenium ..............................................................284