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Unformatted text preview: Markers of protein oxidation by hydroxyl radical and reactive nitrogen species in tissues of aging rats CHRISTIAAN LEEUWENBURGH, 1 POLLY HANSEN, 1 AVIV SHAISH, 1 JOHN O. HOLLOSZY, 1 AND JAY W. HEINECKE 1,2 Departments of 1 Internal Medicine and 2 Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110 Leeuwenburgh, Christiaan, Polly Hansen, Aviv Shaish, John O. Holloszy, and Jay W. Heinecke. Markers of protein oxidation by hydroxyl radical and reactive nitrogen species in tissues of aging rats. Am. J. Physiol. 274 ( Regula- tory Integrative Comp. Physiol. 43): R453–R461, 1998.— Many lines of evidence implicate oxidative damage in aging. Possible pathways include reactions that modify aromatic amino acid residues on proteins. o-Tyrosine is a stable marker for oxidation of protein-bound phenylalanine by hydroxyl radical, whereas 3-nitrotyrosine is a marker for oxidation of protein-bound tyrosine by reactive nitrogen species. To test the hypothesis that proteins damaged by hydroxyl radical and reactive nitrogen accumulate with aging, we used isotope dilution gas chromatography-mass spectrometry to measure levels of o-tyrosine and 3-nitrotyrosine in heart, skeletal muscle, and liver from young adult (9 mo) and old (24 mo) female Long-Evans/Wistar hybrid rats. We also measured these markers in young adult and old rats that received antioxidant supplements ( a-tocopherol, b-carotene, butylated hydroxytoluene, and ascorbic acid) from the age of 5 mo. We found that aging did not significantly increase levels of protein-bound o-tyrosine or 3-nitrotyrosine in any of the tissues. Antioxidant supplementation had no effect on the levels of protein-bound o-tyrosine and 3-nitrotyrosine in either young or old animals. These observations indicate that the o-tyrosine and 3-nitrotyrosine do not increase signifi- cantly in heart, skeletal muscle, and liver in old rats, suggest- ing that proteins damaged by hydroxyl radical and reactive nitrogen species do not accumulate in these tissues with advancing age. nitric oxide; peroxynitrite; a-tocopherol; b-carotene; ascorbic acid; oxidative stress A WEALTH OF INDIRECT EVIDENCE implicates oxidative damage of cellular constituents in aging, as well as in the pathogenesis of the degenerative diseases of later years (1, 4, 16, 23, 27, 32, 33, 35, 38). Overexpression of superoxide dismutase and catalase, two enzymes that scavenge the reactive intermediates superoxide and hydrogen peroxide, respectively, increases the average and maximum life span of Drosophila (28). Moreover, caloric restriction prolongs the life span of rodents and invertebrates. In many of the studies on caloric restric- tion, the level of antioxidant defense mechanisms was increased and the level of oxidative damage was re- duced (reviewed in Refs. 9 and 25). Collectively, these results suggest that reactive intermediates derived from oxidative metabolism may play a causal role in the aging process....
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This note was uploaded on 05/19/2011 for the course BCH 3218 taught by Professor Johnsteward during the Fall '08 term at University of Florida.
- Fall '08