title: Selenoprotein K form an intermolecular diselenide bond with unusually high redox potential.
abstract: Selenoprotein K (SelK) is a membrane protein involved in antioxidant defense, calcium regulation and the ER-associated protein degradation pathway. We found that SelK exhibits a peroxidase activity with a rate that is low but within the range of other peroxidases. Notably, SelK reduced hydrophobic substrates, such as phospholipid hydroperoxides, which damage membranes. Thus, SelK might be involved in membrane repair or related pathways. SelK was also found to contain a diselenide bond-the first intramolecular bond of that kind reported for a selenoprotein. The redox potential of SelK was -257 mV, significantly higher than that of diselenide bonds in small molecules or proteins. Consequently, SelK can be reduced by thioredoxin reductase. These finding are essential for understanding SelK activity and function.
authors.affiliation: Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States.
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States.
authors.forename: Zhengqi
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States. Electronic address: rozovsky@udel.edu.
authors.forename: Sharon
authors.initials: S
authors.lastname: Rozovsky
mesh_terms: D054477:Glutaredoxins / Q000737:chemistry; D005980:Glutathione Reductase / Q000737:chemistry; D006801:Humans; D007700:Kinetics; D008054:Lipid Peroxides / Q000737:chemistry; D009249:NADP / Q000737:chemistry; D010084:Oxidation-Reduction; D018036:Selenium Compounds / Q000737:chemistry*; D051140:Selenoproteins / Q000737:chemistry*; D013379:Substrate Specificity; D013880:Thioredoxin-Disulfide Reductase / Q000737:chemistry; D013879:Thioredoxins / Q000737:chemistry
chemical_list: D054477:Glutaredoxins; D008054:Lipid Peroxides; D018036:Selenium Compounds; D051140:Selenoproteins; C000592898:selenoprotein K, human; D013879:Thioredoxins; D009249:NADP; D005980:Glutathione Reductase; D013880:Thioredoxin-Disulfide Reductase
keywords: Diselenide bond; Peroxidase; Phospholipid hydroperoxide; Selenocysteine; Selenoprotein K