Iron-induced lipid peroxidation and protein modification in endoplasmic reticulum membranes. Protection by stobadine.
Treatment with FeSO(4)/EDTA (0.2 micromol Fe(II) per mg of protein) was used to study the effect of oxidative stress on lipid peroxidation and structural properties of endoplasmic reticulum (ER) membranes isolated from rabbit brain. Oxidative stress resulted in conjugated diene formation and a decrease of 1-anilino-8-naphthalenesulfonate (ANS) fluorescence in a time-dependent manner. In contrast, fluorescence anisotropy of 1, 6-diphenyl-1,3,5-hexatriene was increased early after the initiation of lipid peroxidation and no further increase was observed after 1, 2 and 3 h of peroxidation. FeSO(4)/EDTA treatment was accompanied by formation of conjugates of lipid peroxidation products with membrane proteins, as detected by the increase in fluorescence excitation (350-360 nm) and emission (440-450 nm) maximum. Oxidative stress also induced a marked decrease of the intrinsic fluorescence of aromatic amino acids, suggesting modification or changes in the environment of these amino acid residue(s). The lipid antioxidant, stobadine, completely prevented the changes of ANS fluorescence and production of peroxidized lipid-protein conjugates whereas tryptophan fluorescence was only partially protected. These results suggest that Fe(II) induces both lipid-mediated- and lipid peroxidation independent-modification of ER membrane proteins. The study also demonstrates that stobadine is a potent inhibitor of Fe(II)-induced protein modification.
Kaplán
P
P
Comenius University, Jessenius Faculty of Medicine, Department of Biochemistry, Malá Hora 4, SK-036 01 Martin, Slovak Republic. kaplan@jfmed.uniba.sk
Doval
M
M
Majerová
Z
Z
Lehotský
J
J
Racay
P
P
D000596:Amino Acids / Q000737:chemistry; D000817:Anilino Naphthalenesulfonates / Q000737:chemistry; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001921:Brain / Q000166:cytology / Q000378:metabolism; D002243:Carbolines / Q000494:pharmacology*; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism*; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry; D005609:Free Radicals / Q000378:metabolism; D007425:Intracellular Membranes / Q000187:drug effects / Q000378:metabolism; D007501:Iron / Q000494:pharmacology*; D015227:Lipid Peroxidation / Q000187:drug effects*; D008565:Membrane Proteins / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D011817:Rabbits
D000596:Amino Acids; D000817:Anilino Naphthalenesulfonates; D000975:Antioxidants; D002243:Carbolines; D005456:Fluorescent Dyes; D005609:Free Radicals; D008565:Membrane Proteins; C027132:1-anilino-8-naphthalenesulfonate; D007501:Iron; C100106:dicarbine