Inverse deuterium kinetic isotope effect for peroxidation in human low-density lipoprotein (LDL): a simple test for tocopherol-mediated peroxidation of LDL lipids.
alpha-Tocopherol (alpha-TOH) can act as a pro- or antioxidant for isolated ubiquinol-10-free human low density lipoprotein (LDL). We demonstrate that alpha-TOH is a more potent pro-oxidant than other forms of vitamin E for LDL peroxidation initiated by mild fluxes of aqueous peroxyl radicals and low concentrations of Cu2+. A simple deuterium exchange test shows that alpha-TOH switches from pro- to anti-oxidant at Cu2+:LDL ratios > 2.5. The results suggest that this test may be useful to distinguish 'inhibited' peroxidation of emulsion lipids propagated via the lipid peroxyl radical from that mediated via the antioxidant radical.
D000328:Adult; D003903:Deuterium; D005609:Free Radicals; D006801:Humans; D007700:Kinetics; D015227:Lipid Peroxidation / Q000187:drug effects*; D008077:Lipoproteins, LDL / Q000097:blood* / Q000187:drug effects; D008297:Male; D016877:Oxidants / Q000494:pharmacology*; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D010545:Peroxides; D011865:Radioisotope Dilution Technique; D017382:Reactive Oxygen Species / Q000494:pharmacology; D013329:Structure-Activity Relationship; D013997:Time Factors; D014810:Vitamin E / Q000494:pharmacology*
D005609:Free Radicals; D008077:Lipoproteins, LDL; D016877:Oxidants; D010545:Peroxides; D017382:Reactive Oxygen Species; D014810:Vitamin E; C049375:perhydroxyl radical; D003903:Deuterium