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

Oxidation of low density lipoprotein (LDL) induced by hypochlorous acid (HOCl) leading to LDL-, a minimally oxidized subspecies of LDI., mas investigated. LDL- is characterized by its greater electronegativity and oxidative status, and is found in plasma in vivo. Its concentration was found to he elevated under conditions that predispose humans to atherosclerosis. We found that HOCl also converts LDL rapidly to an even more oxidized stale, identified as LDL2-, which is more electronegative than LDI-. After milder oxidation for short durations, formation of LDL- takes place while less LDL is formed, Under these conditions, addition of methionine not only suppressed further oxidation of LDL but also favored the formation of LDL- over LDL2-, possibly by removing chloramines at lysyl residues of LDL. The presence of lipoprotein-deficient plasma did not present HOCl-mediated conversion of LDL to more electronegative species. It is concluded that the HOCl-mediated conversion of LDL into more electronegative species might be physiologically relevant. (C) 2001 Published bg Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.