Studies on epitopes on low-density lipoprotein modified by 4-hydroxynonenal. Biochemical characterization and determination.
Oxidation of human low-density lipoprotein (LDL) was found to be accompanied by the generation of various reactive aldehydes. One of them, 4-hydroxynonenal (HNE), was shown to modify LDL to a form which represents a good model of oxidized LDL (ox-LDL). In order to investigate the epitopes newly formed on HNE-modified LDL, a polyvalent antiserum to HNE-LDL [anti-(HNE-LDL)] was raised in rabbits and the non-specific components were removed with native LDL coupled to CNBr-Sepharose 4B. Competitive fluorescence immunoassay analysis showed that anti-(HNE-LDL) recognized HNE-LDL, copper-oxidized LDL, HNE-albumin and to a lower extent HNE-modified high-density lipoprotein 3 (HNE-HDL3) and ox-HDL3 but not native LDL. A certain degree of cross-reactivity of the antibody with LDLs modified by either hexanal or 2,4-heptadienal was found. No reaction was obtained with LDL labelled with malondialdehyde. From the abilities of HNE-modified poly(L-amino acids) to compete with HNE-LDL for binding to anti-(HNE-LDL), it is postulated that lysine, tyrosine, arginine and histidine are involved in the formation of HNE-derived epitopes on apolipoprotein B (apo B). Using a double-sandwich fluorescence immunoassay [capture antibody: anti-(apo B); detection antibody: anti-(HNE-LDL)] we found that the HNE-derived epitopes were expressed at a far higher degree in ox-LDL and HNE-LDL than in native LDL.
D000447:Aldehydes / Q000494:pharmacology*; D000596:Amino Acids / Q000032:analysis / Q000276:immunology; D000918:Antibody Specificity; D001055:Apolipoproteins B / Q000032:analysis / Q000276:immunology; D001667:Binding, Competitive; D000939:Epitopes / Q000737:chemistry* / Q000276:immunology; D005453:Fluorescence; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D007118:Immunoassay; D008077:Lipoproteins, LDL / Q000737:chemistry* / Q000276:immunology; D008315:Malondialdehyde / Q000494:pharmacology; D010084:Oxidation-Reduction
D000447:Aldehydes; D000596:Amino Acids; D001055:Apolipoproteins B; D000939:Epitopes; D007106:Immune Sera; D008077:Lipoproteins, LDL; D008315:Malondialdehyde; C027576:4-hydroxy-2-nonenal