Modification of human low-density lipoprotein by the lipid peroxidation product 4-hydroxynonenal.
The effects of the lipid peroxidation product 4-hydroxynonenal on freshly prepared human low-density lipoprotein (LDL) were studied. At a fixed LDL concentration (5.7 mg/ml) the amount of 4-hydroxynonenal incorporated into the LDL increased with increasing aldehyde concentration from 28-30 (0.2 mM) to 140 (1 mM) mol per mol LDL, whereas at a fixed aldehyde concentration (0.2 mM) its incorporation into LDL decreased with increasing LDL concentration from 48 (1 mg LDL/ml) to 26 (12 mg LDL/ml) mol 4-hydroxynonenal bound per mol LDL. Of the total hydroxynonenal taken up 78% was bound to the protein and 21% to the lipid moiety; the remaining 1% was dissolved as free aldehyde in the lipid fraction. Amino acid analysis of the apolipoprotein B revealed that 4-hydroxynonenal attacks mainly the lysine and tyrosine residues and to a lesser extent also serine, histidine and cysteine. Treatment of LDL with 4-hydroxynonenal results in a concentration-dependent increase of the negative charge of the LDL particle as evidenced by its increased electrophoretic mobility. Moreover, 4-hydroxynonenal treatment leads to a partial conversion of the apolipoprotein B-100 into higher molecular weight forms most probably apolipoproteins B-126 and B-151. Compared to malonaldehyde, 4-hydroxynonenal exhibits a much higher capacity to modify LDL and it is therefore believed that this aldehyde is a more likely candidate for being responsible for LDL modification under in vivo lipid peroxidation conditions.
D000447:Aldehydes / Q000097:blood*; D000596:Amino Acids / Q000032:analysis; D001055:Apolipoproteins B / Q000097:blood; D001665:Binding Sites; D002250:Carbon Radioisotopes; D006801:Humans; D007700:Kinetics; D008054:Lipid Peroxides; D008077:Lipoproteins, LDL / Q000097:blood*; D008970:Molecular Weight; D011485:Protein Binding; D011865:Radioisotope Dilution Technique
D000447:Aldehydes; D000596:Amino Acids; D001055:Apolipoproteins B; D002250:Carbon Radioisotopes; D008054:Lipid Peroxides; D008077:Lipoproteins, LDL; C027576:4-hydroxy-2-nonenal