Hypochlorite induces the formation of LDL-, a potentially atherogenic low density lipoprotein subspecies

Oxidation of low density lipoprotein (LDL) induced by hypochlorous acid (HO Cl) leading to LDL-, a minimally oxidized subspecies of LDI., mas investiga ted. LDL- is characterized by its greater electronegativity and oxidative s tatus, and is found in plasma in vivo. Its concentration was found to he el evated under conditions that predispose humans to atherosclerosis, We found that HOCl also converts LDL rapidly to an even more oxidized stale, identi fied as LDL2-, which is more electronegative than LDI-. After milder oxidat ion for short durations, formation of LDL- takes place while less LDL is fo rmed, Under these conditions, addition of methionine not only suppressed fu rther oxidation of LDL but also favored the formation of LDL- over LDL2-, p ossibly by removing chloramines at lysyl residues of LDL. The presence of l ipoprotein-deficient plasma did not present HOCl-mediated conversion of LDL to more electronegative species. It is concluded that tile HOCl-mediated c onversion of LDL into more electronegative species might be physiologically relevant. (C) 2001 Published bg Elsevier Science B.V. on behalf of the Fed eration of European Biochemical Societies.