Detection of Specifically Oxidized Apolipoproteins in Oxidized HDL
Atherosclerosis is associated with dysfunctional HDL, and oxidation of HDL is thought to give rise to HDL becoming dysfunctional. Lipoprotein oxidation represents a complex series of processes that can be assessed by various methods. In general, oxidation mediated by 1-electron or radical oxidants gives rise to lipid hydroperoxides (LOOHs) as the primary product. These LOOHs may then undergo further reactions giving rise to secondary lipid oxidation products and/or oxidation of lipoprotein-associated proteins. Thus, LOOHs specifically oxidize Met residues of apolipoprotein (apo) A-I and A-II (the major proteins of HDL) to MetO. Here we describe an HPLC-based method to detect oxidized HDL containing specifically oxidized forms of apoA-I and apoA-II. This method may be useful to assess the early stages of HDL oxidation in biological samples.
Key wordsOxidized apolipoproteins oxidized HDL lipid peroxidation LOOH MetO antioxidants ultracentrifugation HPLC
- 7.Peng DQ, Wu Z, Brubaker G, et al. (2005) Tyrosine modification is not required for myeloperoxidase-induced loss of apolipoprotein A-I functional activities. J Biol Chem 280, 33775–33784.Google Scholar
- 9.Shao B, Oda MN, Bergt C, et al. (2006) Myeloperoxidase impairs ABCA1-dependent cholesterol efflux through methionine oxidation and site-specific tyrosine chlorination of apolipoprotein A-I. J Biol Chem 14, 9001–9004.Google Scholar
- 17.Garner B, Witting PK, Waldeck AR, Christison JK, Raftery M, Stocker R (1998) Oxidation of high density lipoproteins. I. Formation of methionine sulfoxide in apolipoproteins AI and AII is an early event that correlates with lipid peroxidation and can be enhanced by a-tocopherol. J Biol Chem 273, 6080–6087.CrossRefPubMedGoogle Scholar
- 19.Barclay LRC, Locke SJ, MacNeil JM, VanKessel J (1984) Autoxidation of micelles and model membranes. Quantitative kinetic measurements can be made by using either water-soluble or lipid-soluble initiators with water-soluble or lipid-soluble chain-breaking antioxidants. J Am Chem Soc 106, 2479– 2481.CrossRefGoogle Scholar