title: Selenoprotein P protects low-density lipoprotein against oxidation.
abstract: Selenoprotein P (SeP) is an extracellular glycoprotein with 8-10 selenocysteines per molecule, containing approximately 50% of total selenium in human serum. An antioxidant function of SeP has been postulated. In the present study, we show that SeP protects low-density lipoproteins (LDL) against oxidation in a cell-free in-vitro system. LDL were isolated from human blood plasma and oxidized with CuCl2, 2,2'-azobis(2-amidinopropane) (AAPH) or peroxynitrite in the presence or absence of SeP, using the formation of conjugated dienes as parameter for lipid peroxidation. SeP delayed the CuCl2- and AAPH-induced LDL oxidation significantly and more efficiently than bovine serum albumin used as control. In contrast, SeP was not capable of inhibiting peroxynitrite-induced LDL oxidation. The protection of LDL against CuCl2- and AAPH-induced oxidation provides evidence for the antioxidant capacity of SeP. Because SeP associates with endothelial membranes, it may act in vivo as a protective factor inhibiting the oxidation of LDL by reactive oxygen species.
authors.affiliation: Institute for Biochemistry and Molecular Biology I, Heinrich-Heine-University Duesseldorf, Universitaetsstrasse 1, 40225 Duesseldorf, Germany.
authors.forename: Henrik
authors.initials: H
authors.lastname: Traulsen
authors.forename: Holger
authors.initials: H
authors.lastname: Steinbrenner
authors.forename: Darius P
authors.initials: DP
authors.lastname: Buchczyk
authors.forename: Lars-Oliver
authors.initials: LO
authors.lastname: Klotz
authors.forename: Helmut
authors.initials: H
authors.lastname: Sies
mesh_terms: D000578:Amidines / Q000037:antagonists & inhibitors; D000975:Antioxidants / Q000494:pharmacology*; D003300:Copper / Q000037:antagonists & inhibitors; D006801:Humans; D008077:Lipoproteins, LDL / Q000378:metabolism*; D016877:Oxidants / Q000037:antagonists & inhibitors*; D010084:Oxidation-Reduction; D030421:Peroxynitrous Acid / Q000037:antagonists & inhibitors; D011506:Proteins / Q000378:metabolism / Q000494:pharmacology*; D016601:RNA-Binding Proteins / Q000378:metabolism; D012643:Selenium / Q000378:metabolism; D017279:Selenocysteine / Q000378:metabolism; D051149:Selenoprotein P; D051140:Selenoproteins
chemical_list: D000578:Amidines; D000975:Antioxidants; D008077:Lipoproteins, LDL; D016877:Oxidants; D011506:Proteins; D016601:RNA-Binding Proteins; C121530:SECISBP2 protein, human; D051149:Selenoprotein P; D051140:Selenoproteins; D017279:Selenocysteine; D030421:Peroxynitrous Acid; C046728:2,2'-azobis(2-amidinopropane); D003300:Copper; D012643:Selenium; C029892:cupric chloride