title: Impact of myeloperoxidase-LDL interactions on enzyme activity and subsequent posttranslational oxidative modifications of apoB-100.
abstract: Oxidation of LDL by the myeloperoxidase (MPO)-H2O2-chloride system is a key event in the development of atherosclerosis. The present study aimed at investigating the interaction of MPO with native and modified LDL and at revealing posttranslational modifications on apoB-100 (the unique apolipoprotein of LDL) in vitro and in vivo. Using amperometry, we demonstrate that MPO activity increases up to 90% when it is adsorbed at the surface of LDL. This phenomenon is apparently reflected by local structural changes in MPO observed by circular dichroism. Using MS, we further analyzed in vitro modifications of apoB-100 by hypochlorous acid (HOCl) generated by the MPO-H2O2-chloride system or added as a reagent. A total of 97 peptides containing modified residues could be identified. Furthermore, differences were observed between LDL oxidized by reagent HOCl or HOCl generated by the MPO-H2O2-chloride system. Finally, LDL was isolated from patients with high cardiovascular risk to confirm that our in vitro findings are also relevant in vivo. We show that several HOCl-mediated modifications of apoB-100 identified in vitro were also present on LDL isolated from patients who have increased levels of plasma MPO and MPO-modified LDL. In conclusion, these data emphasize the specificity of MPO to oxidize LDL.
authors.affiliation: Laboratory of Pharmaceutical Chemistry Faculty of Pharmacy, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Cédric
authors.initials: C
authors.lastname: Delporte
authors.forename: Karim Zouaoui
authors.initials: KZ
authors.lastname: Boudjeltia
authors.forename: Caroline
authors.initials: C
authors.lastname: Noyon
authors.forename: Paul G
authors.initials: PG
authors.lastname: Furtmüller
authors.forename: Vincent
authors.initials: V
authors.lastname: Nuyens
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Slomianny
authors.forename: Philippe
authors.initials: P
authors.lastname: Madhoun
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Desmet
authors.forename: Pierre
authors.initials: P
authors.lastname: Raynal
authors.forename: Damien
authors.initials: D
authors.lastname: Dufour
authors.forename: Chintan N
authors.initials: CN
authors.lastname: Koyani
authors.forename: Florence
authors.initials: F
authors.lastname: Reyé
authors.forename: Alexandre
authors.initials: A
authors.lastname: Rousseau
authors.forename: Michel
authors.initials: M
authors.lastname: Vanhaeverbeek
authors.forename: Jean
authors.initials: J
authors.lastname: Ducobu
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Michalski
authors.forename: Jean
authors.initials: J
authors.lastname: Nève
authors.forename: Luc
authors.initials: L
authors.lastname: Vanhamme
authors.forename: Christian
authors.initials: C
authors.lastname: Obinger
authors.forename: Ernst
authors.initials: E
authors.lastname: Malle
authors.forename: Pierre
authors.initials: P
authors.lastname: Van Antwerpen
mesh_terms: D000595:Amino Acid Sequence; D053299:Apolipoprotein B-100 / Q000737:chemistry / Q000378:metabolism*; D016022:Case-Control Studies; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D006868:Hydrolysis; D007674:Kidney Diseases / Q000097:blood / Q000628:therapy; D008077:Lipoproteins, LDL / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010446:Peptide Fragments; D009195:Peroxidase / Q000737:chemistry / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D006435:Renal Dialysis
chemical_list: C569471:APOB protein, human; D053299:Apolipoprotein B-100; D008077:Lipoproteins, LDL; D010446:Peptide Fragments; D006861:Hydrogen Peroxide; D009195:Peroxidase
keywords: 3-chlorotyrosine; apolipoprotein B-100; epitope mapping; hypochlorous acid; inflammation; low density lipoprotein; myeloperoxidase activity