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氨基酸的反应 蛋白质上的残留物。O-酪氨酸是一种稳定的氧化标志物 羟基自由基与蛋白质结合的苯丙氨酸，而 3-硝基酪氨酸是蛋白质结合酪氨酸氧化的标志。 活性氮物种。来检验蛋白质是否 受羟基自由基损伤，活性氮随 老化时，我们使用稳定同位素稀释气相色谱-质谱法 光谱分析(GC/MS)测定o-酪氨酸和 青年心脏、骨骼肌和肝脏中的3-硝基酪氨酸 (9月龄)和(24月龄)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志物 接受抗氧化剂补充剂((-生育酚，(-胡萝卜素，丁化 羟甲苯和抗坏血酸)从5个月大开始。我们发现 衰老并没有显著增加蛋白质结合氧的水平 任何组织中的松香或3-硝基酪氨酸。抗氧化剂 补充对蛋白质结合水平没有影响。 无论是幼年动物还是老年动物的O-酪氨酸和3-硝基酪氨酸。这些 观察表明，o-酪氨酸和3-硝基酪氨酸不 老年人心脏、骨骼肌和肝脏组织含量显著增加 提示羟基自由基损伤的蛋白质和 活性氮物种不会在这些组织中积聚 年事已高。

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.