Selenium. Role of the Essential Metalloid in Health

摘要: Selenium is an essential micronutrient in mammals, but also recognized as toxic excess. It a non-metal with properties that are intermediate between the chalcogen elements sulfur and tellurium. exerts its biological functions through selenoproteins. Selenoproteins contain selenium form of 21st amino acid, selenocysteine (Sec), which analog cysteine sulfur-containing side chain replaced by Se-containing chain. Sec encoded codon UGA, one three termination codons for mRNA translation non-selenoprotein genes. Recognition UGA insertion site instead stop requires sequence (SECIS) element selenoprotein mRNAs unique selenocysteyl-tRNA, both specialized protein factors. Unlike 20 standard acids, biosynthesized from serine on tRNA. Twenty-five selenoproteins human genome. Most genes were discovered bioinformatics approaches, searching SECIS downstream in-frame codons. has been described having stronger nucleophilic electrophilic than cysteine, present catalytic all selenoenzymes. selenoproteins, whose known, involved redox systems signaling pathways. However, several not well characterized terms their function. The field grown dramatically last few decades, research biology providing extensive new information regarding importance health.