Mechanistic aspects of the relationship between low-level chemiluminescence and lipid peroxides in oxidation of low-density lipoprotein

In this study oxidation of low-density lipoprotein (I;DL) induced by differ ent Cu2+ concentrations was investigated. Lipid peroxidation was assessed b y monitoring low-level chemiluminescence (LL-CL), conjugated diene hydroper oxide (CD) and a-tocopherol (TocOH), the major lipophilic antioxidant in LD L, At high Cu2+ concentration, LDL oxidation was characterised by CD format ion, LL-CL emission and TocOH consumption. At low Cu2+ concentration, CD fo rmation was independent of LL-CL and occurred in the presence of TocOH, Thu s, two different mechanisms lead to lipid peroxide formation in LDL, The co mbination of CD assay and LL-CL monitoring makes it possible to distinguish the autocatalytic mechanism of CD formation and that associated with TocOH , found at a high and a low rate of initiation, respectively. (C) 1999 Fede ration of European Biochemical Societies.