Effect of pH on low-density lipoprotein oxidation by O2-./HO2. free radicals produced by gamma radiolysis.
This study aimed to analyze quantitatively the initiation and the consequences of low-density lipoprotein (LDL) peroxidation by O2-./HO2. free radicals produced by gamma radiolysis. The action of increasing radiation doses on aqueous LDL solutions has been monitored simultaneously by several parameters: a decrease in endogenous vitamin E, the formation of thiobarbituric acid-reactive substances (TBARS) and conjugated dienes, the appearance of a differential fluorescence (excitation wavelength = 360 nm), and an increase of the relative electrophoretic mobility. Initial radiation yields (decrease in vitamin E, formation of TBARS) have been determined at pH 7 and pH 5.7 as a function of LDL concentration (from 0.75 to 9 g liter-1). From the comparison of these yields with those of O2-. radicals produced by water radiolysis, we have deduced reaction mechanisms for LDL peroxidation initiated by O2-./HO2. free radicals.
Bonnefont-Rousselot
D
D
Laboratoire de Biochimie, Hôpital de la Salpêtrière, Paris, France.
Gardès-Albert
M
M
Lepage
S
S
Delattre
J
J
Ferradini
C
C
D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D005609:Free Radicals; D005720:Gamma Rays; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008077:Lipoproteins, LDL / Q000097:blood / Q000302:isolation & purification / Q000528:radiation effects*; D010084:Oxidation-Reduction; D010545:Peroxides; D013050:Spectrometry, Fluorescence; D013481:Superoxides; D017392:Thiobarbituric Acid Reactive Substances / Q000032:analysis; D014810:Vitamin E / Q000494:pharmacology
D005609:Free Radicals; D008077:Lipoproteins, LDL; D010545:Peroxides; D017392:Thiobarbituric Acid Reactive Substances; D013481:Superoxides; D014810:Vitamin E; C049375:perhydroxyl radical