Structural changes in oxidative modification of low-density lipoprotein: investigation using lipid peroxidation...

It is well recognized that oxidative modification of low-density lipoprotein (LDL) accelerates atherogenesis of the arterial vascular wall. In this study, we examined the relationship between various methods of measuring the extent of oxidation, namely lipid peroxidation products, surface charge, and spectrophotometric patterns. LDL was isolated from fresh human normal plasma by centrifugation and was oxidized by incubating with copper ions. Apolipoprotein B was isolated from the LDL solution. We also prepared artificial lipid particles composed of cholesterol linolenate, triolein, and phosphatidylcholine. Our results suggest that lipid peroxidation begins drastically in 30-60 min, while the abolition of the positive charge on apoliproproteins is accelerated after 60 min. We found a characteristic change in the spectrophotometric pattern during the process and conclude that the spectrophotometric absorption ration at 232 and 203 nm is a useful measure of in vitro oxidation of LDL.