BIOLOGICAL CONSEQUENCES OF PROTEIN OXIDATION

蛋白质氧化的生物学后果

• 批准号: 2569003
• 负责人: E B SHACTER
• 金额: --
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/2569003
• 关键词: carbohydrate metabolism; carbonyl compound; fibrinogen; glycoproteins; human tissue; hydrogen peroxide; lipid metabolism; oncoproteins; oxidation; oxidative stress; protease inhibitor; protein metabolism; proteolysis; western blottings

Proteins can become oxidized under a variety of conditions in vitro and in vivo. Specific polypeptide changes include formation of aldehyde (carbonyl) groups, generation of methionine sulfoxide and dityrosine, rearrangement of disulfide bonds, cleavage of peptide bonds, and protein aggregation. The consequences of protein oxidative modifications are varied. Some modifications lead to differential susceptibility of a protein to proteolytic cleavage while others cause gain or loss of biological activity. For example, we have found that oxidative modification of fibrinogen inhibits ability of the protein to undergo clotting. Conversely, oxidation of plasma protease inhibitors can lead to an increase of clotting activity. Our research involves examination of the conditions under which proteins acquire oxidative modifications and development of assays that provide a correct assessment of the types of modifications incurred. We determined that the carbohydrate moieties of glycoproteins do not undergo oxidative modification to carbonyl groups under conditions that oxidize amino acid side chains. In addition, we validated the use of a Western blot assay for protein carbonyls for use on glycoproteins. Current studies are aimed at developing an appropriate in vitro model for studying protein oxidative modification in cells exposed to varying growth conditions, including oxidative stress. Because cellular lipids are also targets for oxidative attack and can modify proteins through conjugation reactions, it is important to distinguish between lipid-derived protein modifications and direct protein oxidative modification. We have chosen to work with lymphoma cells that express different levels of the oncogene bcl-2 because resistance to oxidative processes is thought to correlate with expression of high levels of the Bcl-2 protein. The biological consequences of oxidative reactions will be explored by comparing the effects of H2O2 treatment on cells that are either sensitive or resistant to this oxidant.

蛋白质可以在体外多种条件下被氧化， in vivo. 特异性多肽变化包括醛的形成 （羰基）基团，甲硫氨酸亚砜和二酪氨酸的产生， 二硫键重排、肽键断裂和蛋白质 聚合来 蛋白质氧化修饰的后果是 各种各样。 一些修改导致不同的磁化率的一个 蛋白质的蛋白水解裂解，而其他引起的增益或损失， 生物活性 例如，我们已经发现， 纤维蛋白原的修饰抑制了蛋白质经历 凝血 相反，血浆蛋白酶抑制剂的氧化可导致 凝血活性的增加。 我们的研究涉及检查 蛋白质获得氧化修饰的条件 并开发出能正确评估 发生的修改。 我们确定碳水化合物部分 的糖蛋白不进行氧化修饰为羰基 在氧化氨基酸侧链的条件下。 另外我们 验证了蛋白质羰基的蛋白质印迹测定法的使用， 对糖蛋白的影响 目前的研究旨在制定一个适当的 研究细胞中蛋白质氧化修饰的体外模型 暴露于不同的生长条件，包括氧化应激。 因为细胞脂质也是氧化攻击的目标， 通过缀合反应修饰蛋白质，重要的是 区分脂质衍生的蛋白质修饰和直接修饰 蛋白质氧化修饰 我们选择与淋巴瘤 表达不同水平的癌基因bcl-2的细胞， 抗氧化过程被认为与表达相关， 高水平的Bcl-2蛋白。 的生物学后果 氧化反应将探讨通过比较的影响H2 O2 对这种药物敏感或耐药的细胞进行治疗 氧化剂