Selenoprotein P protects low-density lipoprotein against oxidation.
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.
Traulsen
Henrik
H
Institute for Biochemistry and Molecular Biology I, Heinrich-Heine-University Duesseldorf, Universitaetsstrasse 1, 40225 Duesseldorf, Germany.
Steinbrenner
Holger
H
Buchczyk
Darius P
DP
Klotz
Lars-Oliver
LO
Sies
Helmut
H
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
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