title: Inactivation of NADP+-dependent isocitrate dehydrogenase by lipid peroxidation products.
abstract: Membrane lipid peroxidation processes yield products that may react with proteins to cause oxidative modification. Recently, we demonstrated that the control of cytosolic and mitochondrial redox balance and oxidative damage is one of the primary functions of NADP+-dependent isocitrate dehydrogenase (ICDH) through to supply NADPH for antioxidant systems. When exposed to lipid peroxidation products, such as malondialdehyde (MDA), 4-hydroxynonenal (HNE) and lipid hydroperoxide, ICDH was susceptible to oxidative damage, which was indicated by the loss of activity and the formation of carbonyl groups. The structural alterations of modified enzymes were indicated by the change in thermal stability, intrinsic tryptophan fluorescence and binding of the hydrophobic probe 8-anilino 1-napthalene sulfonic acid. Upon exposure to 2,2'-azobis(2-amidinopropane) hydrochloride (AAPH), which induces lipid peroxidation in membrane, a significant decrease in both cytosolic and mitochondrial ICDH activities were observed in U937 cells. Using immunoprecipitation and immunoblotting, we were able to isolate and positively identify HNE adduct in mitochondrial ICDH from AAPH-treated U937 cells. The lipid peroxidation-mediated damage to ICDH may result in the perturbation of the cellular antioxidant defense mechanisms and subsequently lead to a prooxidant condition.
authors.affiliation: Department of Biochemistry, College of Natural Sciences, Kyungpook National University, Taegu 702-701, South Korea.
authors.forename: Joon-Hyuck
authors.initials: JH
authors.lastname: Yang
authors.forename: Eun Sun
authors.initials: ES
authors.lastname: Yang
authors.forename: Jeen-Woo
authors.initials: JW
authors.lastname: Park
mesh_terms: D000447:Aldehydes / Q000378:metabolism / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000378:metabolism / Q000494:pharmacology*; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D007521:Isocitrate Dehydrogenase / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D015227:Lipid Peroxidation / Q000187:drug effects / Q000502:physiology*; D008054:Lipid Peroxides / Q000378:metabolism / Q000494:pharmacology; D008315:Malondialdehyde / Q000378:metabolism / Q000494:pharmacology; D009249:NADP / Q000378:metabolism*; D010084:Oxidation-Reduction; D017382:Reactive Oxygen Species / Q000378:metabolism; D013997:Time Factors; D020298:U937 Cells
chemical_list: D000447:Aldehydes; D004791:Enzyme Inhibitors; D008054:Lipid Peroxides; D017382:Reactive Oxygen Species; D008315:Malondialdehyde; D009249:NADP; D007521:Isocitrate Dehydrogenase; C039355:isocitrate dehydrogenase (NADP+); D005978:Glutathione; C027576:4-hydroxy-2-nonenal