Studies of selenoproteins and their medical importance
Selenium is a basic element originally discovered in 1817 by Berzelius, one of the first professors of Karolinska Institutet. As a nutritional trace element, selenium has importance for human health and disease mainly due to the properties of the element as a constituent of selenoproteins. Selenoproteins carry a seleniumcontaining selenocysteine (Sec) residue, the 21st amino acid, which has unique biochemical properties. Sec is a sulfur-for-selenium substituted analog of Cys that is co-translationally incorporated at predefined UGA codons through an expansion of the genetic code. The human genome encodes 25 selenoproteins, e.g. thyroid hormone deiodinases, thioredoxin reductases (TrxR's) and glutathione peroxidases. Selenium is highly important for mammals due to vital roles of some selenoproteins and knockout mice deficient in tRNA for Sec die at implantation. Thioredoxin reductases belong to the class of essential selenoproteins in mammals, linking all the function of the thioredoxin system to selenium status. Our work is focused on the production of recombinant selenoproteins with studies of their function and importance in medicine, with a special focus on human TrxR1 in relation to disease and the development of biotechnological applications of synthetic selenoproteins.