OXIDIZED AMINO ACIDS IN URINE OF RATS POTENTIAL MARKERS FOR ASSESSING STRESS

蛋白质的氧化损伤与疾病和 衰老。体外研究表明，两种非天然氨基酸， O，O4-二酪氨酸和O-酪氨酸是蛋白质的稳定标记物 氧化。我们已经调查了化验这些物质的可能性 尿液中的化合物可以提供一种非侵入性的方法来测定尿液中的 体内蛋白质氧化的研究。同位素稀释气 用气相色谱/质谱法测定血药浓度 增龄性骨骼肌和尿液中的O，O4-二酪氨酸和邻酪氨酸 接受两种干预的大鼠&饮食中的抗氧化剂 补充和运动训练。在久坐的大鼠和 运动训练的大鼠，抗氧化治疗降低了水平 骨骼肌中蛋白质结合的o，o4-二氢酪氨酸。相比之下， 抗氧化治疗或运动训练对o-酪氨酸的影响最小 在这个组织中的含量。尿液中氧化氨基酸的水平 样本反映了骨骼肌蛋白质的情况。量化 因此，尿液中氧化氨基酸的水平可作为一种 体内氧化应激的非侵入性测量，因为它们在 与骨骼中蛋白质结合的氧化氨基酸水平平行 肌肉。

Oxidative damage of proteins has been implicated in disease and aging. In vitro studies demonstrate that two unnatural amino acids, o,o4-dityrosine and o-tyrosine, are stable markers of protein oxidation. We have investigated the possibility that assaying these compounds in urine could provide a noninvasive way to determine levels of protein oxidation in vivo. Isotope dilution gas chromatography/mass spectrometry was used to quantify levels of o,o4-dityrosine and o-tyrosine in skeletal muscle and urine of aging rats subjected to two interventions > dietary antioxidant supplementation and exercise training. In both sedentary rats and exercise-trained rats, antioxidant therapy reduced levels of protein-bound o,o4-dityrosine in skeletal muscle. In contrast, antioxidant therapy or exercise training minimally affected o-tyrosine levels in this tissue. Levels of the oxidized amino acids in urine samples mirrored those of skeletal muscle proteins. Quantification of the lev els of oxi dized amino acids in urine may thus serve as a noninvasive measure of oxidative stress in vivo because they change in parallel with levels of protein-bound oxidized amino acids in skeletal muscle.