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Updated: May 3, 2026
Cell-free Biochemical Fluorometric Enzymatic Assay for High-throughput Measurement of Lipid Peroxidation in High Density Lipoprotein
Published on: October 12, 2017
Impact of myeloperoxidase-LDL interactions on enzyme activity and subsequent posttranslational oxidative
Cédric Delporte1, Karim Zouaoui Boudjeltia, Caroline Noyon
1Laboratory of Pharmaceutical Chemistry Faculty of Pharmacy, Université Libre de Bruxelles, Brussels, Belgium.
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.
Insights
Myeloperoxidase (MPO) significantly enhances its activity when bound to LDL, leading to specific modifications of apoB-100. These MPO-induced LDL modifications are observed in patients, highlighting MPO
Area of Science:
- Biochemistry
- Cardiovascular Research
- Molecular Biology
Background:
- Oxidation of low-density lipoprotein (LDL) by myeloperoxidase (MPO) is crucial in atherosclerosis development.
- Understanding the interaction between MPO and LDL is key to elucidating disease mechanisms.
Purpose of the Study:
- To investigate MPO's interaction with native and modified LDL.
- To identify posttranslational modifications on apoB-100 induced by MPO in vitro and in vivo.
Main Methods:
- Amperometry to measure MPO activity on LDL surface.
- Circular dichroism to observe MPO structural changes.
- Mass spectrometry (MS) to identify apoB-100 modifications by hypochlorous acid (HOCl).
Main Results:
- MPO activity increased up to 90% upon adsorption to LDL, with associated structural changes.
- Identified 97 peptides with HOCl-mediated modifications on apoB-100.
- Observed HOCl-mediated apoB-100 modifications in LDL from high cardiovascular risk patients, correlating with plasma MPO levels.
Conclusions:
- MPO specifically oxidizes LDL, leading to distinct apoB-100 modifications.
- In vitro findings are relevant in vivo, confirming MPO's role in atherosclerosis pathogenesis.
- MPO-modified LDL serves as a potential biomarker in cardiovascular risk assessment.
