Presence of aldehydic epitopes on a minor low-density lipoprotein fraction.
A more negatively charged low-density lipoprotein (LDL), named minor LDL (mi-LDL), was separated by ionic exchange chromatography and further characterized. This mi-LDL contained lower amounts of polyunsaturated fatty acids, alpha- or gamma- tocopherol, but higher amounts of lipid hydroperoxides than the major LDL fraction (ma-LDL). We show here for the first time that apoB of mi-LDL is modified by lipid peroxidation products, such as 4-hydroxynonenal (4-HNE) and malondialdehyde (MDA). Using polyclonal antibodies, generated against 4-HNE- or MDA-LDL and apoB, the ratio of 4-HNE- or MDA-derived epitopes to apoB of mi-LDL and ma-LDL was estimated by means of a solid phase fluorescence immunoassay. The ratio of 4-HNE-derived epitopes to apoB on mi-LDL was fourfold higher, while the ratio of MDA-derived epitopes to apoB was twofold higher, compared with the ratios obtained with ma-LDL. In a competition assay with mi- and ma-LDL, only mi-LDL was an effective competitor to inhibit the immunoreaction of anti-4-HNE-LDL with 4-HNE-LDL (by 24%) and of anti-MDA-LDL with MDA-LDL (by 10%).
Institute of Medical Biochemistry, Karl-Franzens Universität, Graz, Austria.
J
J
Greilberger
X
X
Wang
G
G
Ledinski
Q
Q
Chen
G
G
Jürgens
D000447:Aldehydes / Q000276:immunology*; D000975:Antioxidants / Q000378:metabolism; D001782:Blood Donors; D005591:Chemical Fractionation; D002852:Chromatography, Ion Exchange; D004563:Electrochemistry; D000939:Epitopes; D005227:Fatty Acids / Q000097:blood; D005470:Fluorometry; D005609:Free Radicals; D006801:Humans; D007118:Immunoassay / Q000379:methods; D008054:Lipid Peroxides / Q000097:blood; D008077:Lipoproteins, LDL / Q000276:immunology*; D008315:Malondialdehyde / Q000276:immunology
D000447:Aldehydes; D000975:Antioxidants; D000939:Epitopes; D005227:Fatty Acids; D005609:Free Radicals; D008054:Lipid Peroxides; D008077:Lipoproteins, LDL; D008315:Malondialdehyde; C027576:4-hydroxy-2-nonenal