Major differences in oxysterol formation in human low density lipoproteins(LDLs) oxidized by (OH)-O-center dot/O-2(center dot-) free radicals or by copper

The aim of our study was to determine the oxysterol formation in low densit y lipoproteins (LDLs) oxidized by defined oxygen free radicals ((OH)-O-./O- 2(.-)). This was compared to the oxysterol produced upon the classical copp er oxidation procedure. The results showed a markedly lower formation of ox ysterols induced by (OH)-O-./O-2(.-) free radicals than by copper and thus suggested a poor ability of these radicals to initiate cholesterol oxidatio n in LDLs, Moreover, the molecular species of cholesteryl eater hydroperoxi des produced by LDL copper oxidation seemed more labile than those formed u pon (OH)-O-./O-2(.-)-induced oxidation, probably due to their degradation b y reaction with copper ions. (C) 1999 Federation of European Biochemical So cieties.