Aggregation of LDL with chondroitin-4-sulfate makes LDL oxidizable in the presence of water-soluble antioxidants.
The content of plasma and arterial interstitial fluid in water-soluble antioxidants makes it unlikely for low-density lipoprotein (LDL) to oxidize by the oxidation mechanisms most frequently discussed. By aggregation of LDL in the presence of chondroitin-4-sulfate (C-4-S), but not with chondroitin-6-sulfate or sphingomyelinase, a complex arises which can oxidize in the presence of 20 microM ascorbate and 300 microM urate. This oxidation sensitivity even persists after the gel-filtration of an LDL/C-4-S/Cu(2+) complex, indicating entrapment of Cu(2+) within. This corresponds well to the known ability of C-4-S to bind copper ions and is a potential mechanism by which LDL oxidation in the arterial intima is facilitated after prolonged retention by the extracellular matrix.
Abuja
Peter M
PM
Institute of Molecular Biology, Biochemistry and Microbiology, SFB Biomembrane Research Center, University of Graz, Schubertstrasse 1, A-8010, Graz, Austria. peter.abuja@kfunigraz.ac.at
D000975:Antioxidants / Q000494:pharmacology*; D002809:Chondroitin Sulfates / Q000378:metabolism*; D006801:Humans; D015227:Lipid Peroxidation; D008077:Lipoproteins, LDL / Q000378:metabolism*; D012995:Solubility; D014867:Water
D000975:Antioxidants; D008077:Lipoproteins, LDL; D014867:Water; D002809:Chondroitin Sulfates