Physical changes of low-density lipoprotein on oxidation.

Human LDL samples from different individuals were oxidized in three different ways. All oxidized LDL samples exhibited lower temperature of the thermotropic transition and lower content of the helical fraction of apoprotein B than the related native LDL. The observed decrease of the thermotropic transition temperature was up to 2 degrees C. The lowering of the transition temperature is qualitatively explained in terms of the 'impurity'-perturbed molecular field in the lipid core. The reduction of helicity of the apoprotein was drastic; in some samples the helicity was reduced by more than 50%.