POSSIBLE INVOLVEMENT OF RADICAL REACTIONS IN DESIALYLATION OF LDL

The role of oxidatively modified LDL in the pathogenesis of atheroscle rosis has been well documented, These studies have focused on modifica tions of lipid and protein parts of LDL. Recently desialylated LDL has received attention in relation to atherosclerosis and coronary artery disease. We examined the possible involvement of radical reactions in desialylation of LDL. Human LDL was subjected to oxidative damage usi ng Cu2+ ion. As the conjugated dienes monitored by absorption at 234 n m increased, the content of sialic acid decreased steadily. Both the e levation of conjugated diene and the decrease of sialic acid were inhi bited by beta-mercaptoethanol, a typical radical scavenger. Besides, b oth butylated hydroxytoluene and a nitrogen atmosphere inhibited the d ecrease of sialic acid. These inhibition experiments suggested that si alic acid moieties in LDL were reactive toward radicals. (C) 1997 Fede ration of European Biochemical Societies.