Selenium-Dependent Antioxidant Enzymes: Actions and Properties of Selenoproteins

Abstract

Unlike other essential trace elements that interact with proteins in the form of cofactors, selenium (Se) becomes co-translationally incorporated into the polypeptide chain as part of 21st naturally occurring amino acid, selenocysteine (Sec), encoded by the UGA codon. Any protein that includes Sec in its polypeptide chain is defined as selenoprotein. Members of the selenoproteins family exert various functions and their synthesis depends on specific cofactors and on dietary Se. The Se intake in productive animals such as chickens affect nutrient utilization, production performances, antioxidative status and responses of the immune system. Although several functions of selenoproteins are unknown, many disorders are related to alterations in selenoprotein expression or activity. Selenium insufficiency and polymorphisms or mutations in selenoproteins’ genes and synthesis cofactors are involved in the pathophysiology of many diseases, including cardiovascular disorders, immune dysfunctions, cancer, muscle and bone disorders, endocrine functions and neurological disorders. Finally, heavy metal poisoning decreases mRNA levels of selenoproteins and increases mRNA levels of inflammatory factors, underlying the antagonistic effect of Se. This review is an update on Se dependent antioxidant enzymes, presenting the current state of the art and is focusing on results obtained mainly in chicken.

Oxidation‐Responsive Materials: Biological Rationale, State of the Art, Multiple Responsiveness, and Open Issues

“…Replacing sulfur atoms with selenium is a relatively easy task—same valence, similar chemistry—and is a common step to provide oxidation‐responsive functions: selenocysteine is a natural amino acid (codon: UGA) that can replace cysteine (codons: TGT, TGC) in a number of enzymes collectively referred to as selenoproteins; these are important antioxidants, see also MrsB in Figure . With this in mind, the introduction of selenium in macromolecules can in principle be advantageous in terms of ROS response.…”

Arsenic intoxication: general aspects and chelating agents

“…The protective effect of antioxidant trace elements upon simultaneous exposure with toxic metals has been shown on various cell cultures (Binte Hossain et al 2018). Human selenoproteins protect the cells from damages caused by cellular protein oxidation (Steinbrenner et al 2016;Zoidis et al 2018). Selenium counteracts and reduces the toxicity of heavy metals such as Hg, Cd, Pb, and hexavalent chromium in the body (Antonyak et al 2008(Antonyak et al , 2018.…”

Amiodarone-induced thyrotoxicosis type 2: predictors and treatment options

“…Каталитическое ядро системы генерации Н 2 О 2 составляют ферменты оксидазы: DUOX1, DUOX2 и их факторы созревания: DUOXA1, DUOXA2 [26]. Они отвечают за производство адекватных концентраций активных форм кислорода для регулярного, непрерывного, соразмерного биосинтеза гормонов ЩЖ [27]. Высокая концентрация H 2 O 2 вызывает апоптоз, критическая -некроз тиреоцитов.…”