BIOLOGICAL CONSEQUENCES OF PROTEIN OXIDATION

蛋白质在体外可以在各种条件下被氧化， 在活体内。特定多肽的变化包括醛的形成 (羰基)基团，甲硫氨酸亚砜和二叔丁基的生成， 二硫键重排、多肽键断裂和蛋白质 聚合。蛋白质氧化修饰的后果是 多种多样。一些修改导致了一种 蛋白质到蛋白水解性切割，而其他导致得或失 生物活性。例如，我们已经发现氧化 纤维蛋白原的修饰抑制了蛋白质的能力 凝血。相反，血浆蛋白水解酶抑制物的氧化可导致 凝血活性的增加。我们的研究包括考试 蛋白质在哪些条件下获得氧化修饰 以及开发提供对类型的正确评估的分析方法 所发生的修改。我们确定了碳水化合物的部分 的糖蛋白不会被氧化修饰成羰基。 在氧化氨基酸侧链的条件下。此外，我们 验证了蛋白质羰基的蛋白质印迹分析的使用 在糖蛋白上。目前的研究旨在开发一种适当的 研究细胞内蛋白质氧化修饰的体外模型 暴露在不同的生长条件下，包括氧化应激。 因为细胞脂质也是氧化攻击的目标，可以 通过偶联反应修饰蛋白质，重要的是 区分脂类衍生蛋白修饰和直接修饰 蛋白质氧化修饰。我们选择了与淋巴瘤合作 表达不同水平的癌基因bcl2的细胞是因为 对氧化过程的抵抗被认为与基因表达有关 高水平的Bc l-2蛋白。病毒的生物学后果 将通过比较过氧化氢的影响来探索氧化反应 对此敏感或耐药的细胞的治疗 氧化剂。

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.