Antioxidants and oxidative damage in mitochondria

描述(申请人提供)：本项目的重点在于小抗氧化剂分子在防止和/或修复线粒体硝化蛋白质方面的作用。在暴露于一氧化氮的生物系统中，蛋白质发生硝化作用。在酪氨酸残基上加一个硝基，生成3-硝基酪氨酸，被认为是翻译后修饰，是信号转导途径的一部分，或者是“正常”氧化应激的结果。 在这项研究中，我们将表征产生一氧化氮的线粒体中蛋白质硝化的机制，因为这些细胞器在维持细胞ATP、β-氧化、血红素合成和其他功能方面具有重要作用。我们的研究旨在了解硝化作用引起的动力学和结构变化，以及水果和蔬菜中存在的天然抗氧化剂如何防止/逆转这种影响。黄酮类、香豆素和儿茶素的抗氧化作用将从羟基取代、环的共轭和羟基的O-甲基化来研究，以阐明结构和功能之间的联系。为此，这项建议的具体目标如下： 1.探讨线粒体蛋白质硝化的分子机制 2.阐明线粒体中蛋白质硝化的生物学意义 3.天然黄酮类化合物在消除蛋白质硝化中的构效关系，以及 4.含黄酮饲料在硝化胁迫下的生物利用度。

DESCRIPTION (provided by applicant): The focus of this project resides on the role of small antioxidant molecules on the prevention and/or repair of nitrated proteins in mitochondria. Protein nitration occurs in biological systems exposed to nitric oxide. The addition of a nitro group to a tyrosine residue, yielding 3-nitrotyrosine, has been claimed to be a posttranslational modification, part of signal transduction pathways, or a result of "normal" oxidative stress. In this study, we will characterize the mechanism underlying the nitration of proteins in nitric oxide-producing mitochondria, given the important role that these organelles have in the maintenance of cellular ATP, beta-oxidation, heme synthesis, and other functions. Our studies will be aimed at understanding the kinetic and structural changes caused by nitration, and how naturally occurring antioxidants -- present in fruits and vegetables may prevent/reverse this effect. The antioxidant effect of flavonoids, coumarins, and catechins will be studied in terms of hydroxyl substitution, conjugation of rings, and o-methylation of hydroxyl groups to elucidate an association between structure and function. To this end, the specific aims of this proposal are the following: 1. Investigate the molecular mechanisms of mitochondrial protein nitration 2. Elucidate the biological relevance of protein nitration in mitochondria 3. Structure-activity association of naturally occurring flavonoids in the abrogation of protein nitration, and 4. Bioavailability of flavonoids containing diets in nitrative stress.