Oxidation of low-density lipoproteins produces levuglandin-protein adducts.
Free-radical oxidation of human low-density lipoprotein (LDL) produces levuglandin (LG)-protein adducts that were detected with an enzyme-linked immunosorbent assay using LGE2-KLH antibodies which recognize LGE2-derived pyrroles. The level of immunoreactivity increases with time of oxidation and reaches a maximum by 8 h. The yield of pyrrole varies nonlinearly with the level of LG adduction to LDL. At low LG:LDL ratios, such as those detected in oxidized LDL, the reaction of primary amino groups with LGE2 produces mostly non-pyrrole adducts that are not immunoreactive. Concomitant phospholipolysis must occur if the generation of immunoreactive epitopes in LDL involves oxidation of arachidonyl phospholipids. Thus, since a protein adduct prepared from synthetic LGE2-2-lysophosphatidylcholine ester showed, at most, only 0.5% cross-reactivity with the LGE2-KLH antibodies, the epitopes detected in oxidized LDL are almost certainly not protein adducts of LG-phospholipid esters. As expected, hydrolysis of the carboxylic ester in the protein adduct of LGE2-2-lysophosphatidylcholine ester by treatment with phospholipase A2 produced a fully immunoreactive LGE2-protein adduct.
Salomon
R G
RG
Department of Chemistry, Case Western Reserve University, Cleveland, Ohio 44106-7078, USA. rgs@po.cwru.edu
Subbanagounder
G
G
Singh
U
U
O'Neil
J
J
Hoff
H F
HF
D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay; D005609:Free Radicals / Q000737:chemistry; D006801:Humans; D066298:In Vitro Techniques; D008074:Lipoproteins / Q000138:chemical synthesis*; D008077:Lipoproteins, LDL / Q000737:chemistry* / Q000378:metabolism; D010084:Oxidation-Reduction; D010713:Phosphatidylcholines / Q000138:chemical synthesis / Q000737:chemistry; D011458:Prostaglandins E / Q000138:chemical synthesis* / Q000378:metabolism; D012709:Serum Albumin / Q000737:chemistry
D005609:Free Radicals; D008074:Lipoproteins; D008077:Lipoproteins, LDL; D010713:Phosphatidylcholines; D011458:Prostaglandins E; D012709:Serum Albumin; C047684:levuglandin E2