MARKERS OF PROTEIN OXIDATION BY HYDROXYL RADICAL & REACTIVE NITROGEN SPECIES

许多证据表明氧化损伤与衰老有关。 可能的途径包括修饰芳香族氨基酸的反应 蛋白质上的残基。 邻酪氨酸是一种稳定的氧化标记物， 蛋白质结合苯丙氨酸的羟基自由基，而 3-硝基酪氨酸是蛋白结合酪氨酸氧化的标志物， 活性氮 为了验证蛋白质 羟基自由基和活性氮的积累， 老化，我们用稳定同位素稀释气相色谱-质谱 用气相色谱/质谱法（GC/MS）测定邻酪氨酸的水平， 3-青年人心脏、骨骼肌和肝脏中硝基酪氨酸 （9个月）和老年（24个月）雌性Long Evans/Wistar杂交大鼠。 我们还测量了年轻成年大鼠和老年大鼠的这些标记物， 接受抗氧化剂补充剂（（-生育酚，（-胡萝卜素，丁基 羟基甲苯和抗坏血酸）。 我们发现 衰老并没有显著增加蛋白质结合的O-TY水平， 酪氨酸或3-硝基酪氨酸。 抗氧化 补充对蛋白结合水平没有影响， o-酪氨酸和3-硝基酪氨酸。 这些 观察表明，邻酪氨酸和3-硝基酪氨酸不 在老年人心脏、骨骼肌和肝脏中显著增加 大鼠，这表明蛋白质被羟基自由基和 活性氮不会在这些组织中积累， 年龄增长。

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 stable isotope dilution gas chromatography-mass spectrometry (GC/MS) to measure levels of o-tyrosine and 3-nitrotyrosine in heart, skeletal muscle and liver from young adult (9 months) and old (24 month) female Long Evans/Wistar hybrid rats. We also measured these markers in young adult and old rats that received antioxidant supplements ((-tocopherol, (-carotene, butylated hydroxytoluene and ascorbic acid) from the age of 5 months. We found that aging did not significantly increase levels of protein-bound o-ty rosine 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 significantly in heart, skeletal muscle and liver in old rats, suggesting that proteins damaged by hydroxyl radical and reactive nitrogen species do not accumulate in these tissues with advancing age.