Peroxynitrite Modification of Enzymes

与早先未发表的观察结果形成对比的是 实验室，据其他工作人员报告说，修改 过氧亚硝酸根对蛋白质的作用导致某些氨基的转化 从酸性残留物到甲酰基衍生物。我们之间的差异 结果和早些时候报道的结果已经得到解决。这是由于 其他工人没有考虑到 蛋白质分光光度测量中的光散射 羰基含量。尽管如此，鉴于羰基 蛋白质含量是被广泛接受的氧化应激指标。 已被用作衰老过程中氧化损伤的标志 在许多疾病中，我们进一步研究了 由过氧亚硝酸盐产生的蛋白质。我们证实了我们早先的发现 谷氨酰胺合成酶蛋氨酸残基的氧化 生理浓度的亚硝酸根强烈抑制过亚硝酸根 二氧化碳，酪氨酸残基的硝化几乎是 完全依赖于二氧化碳的存在。我们 还确认过亚硝酸根不会产生显著的 生理浓度下的蛋白质羰基含量 氢离子和二氧化碳。然而，对中国的依赖 二氧化碳上的这些反应随二氧化碳浓度的不同而不同 氢离子。这些结果强调了 控制氢离子浓度和二氧化碳 体外反应混合物水平的研究旨在确定 过氧亚硝酸根修饰蛋白质。他们进一步展示了 只有边际水平的蛋白质羰基是由 过氧亚硝酸根在所考察的任何实验条件下。它 因此，过氧亚硝酸盐不太可能对 在此期间观察到蛋白质羰基水平的增加 衰老和各种疾病。

In contrast to earlier unpublished observations in this laboratory, it was reported by other workers that the modification of proteins by peroxynitrite leads to the conversion of some amino acid residues to carbonyl derivatives. The discrepancy between our results and those reported earlier has been resolved. It is due to the failure of the other workers to take into account the contribution of light scattering in their spectrophotometric measurements of protein carbonyl content. Nevertheless, in view of the fact that the carbonyl content of proteins is a widely accepted measure of oxidative stress and has been used as a marker of oxidative damage during aging and in many diseases, we investigated further the modification of proteins by peroxynitrite. We confirmed our earlier findings that the oxidation of methionine residues of glutamine synthetase by peroxynitrite is strongly inhibited by physiological concentrations of carbon dioxide, and that the nitration of tyrosine residues is almost completely dependent on the presence of carbon dioxide. We confirmed also that peroxynitrite does not generate significant amounts of protein carbonyl groups at physiological concentrations of hydrogen ion and carbon dioxide. However, the dependence of these reactions on carbon dioxide varies with the concentration of hydrogen ion. These results emphasize the importance of controlling the hydrogen ion concentration and carbon dioxide levels of reaction mixtures in vitro in studies designed to determine the modification of proteins by peroxynitrite. They show further that only marginal levels of protein carbonyl are generated by peroxynitrite under any of the experimental conditions examined. It is therefore unlikely that peroxynitrite contributes significantly to the increase in levels of protein carbonyl groups observed during aging and in various diseases.