MAILLARD REACTIONS AND OXIDATION IN CATARACTOGENESIS

白内障发生中的美拉德反应和氧化

• 批准号: 6329537
• 负责人: Ram H Nagaraj
• 金额: $ 20.24万
• 依托单位: CASE WESTERN RESERVE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-09-01 至 2001-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6329537
• 关键词: amino group; carbon sulfur lyase; cataract; chemical reaction; crosslink; crystallins; enzyme linked immunosorbent assay; free radical oxygen; glutathione; glycation; glycosylation; human tissue; laboratory rat; lens proteins; organ culture; oxidative stress; pathologic process

DESCRIPTION: Several mechanisms have been put forward to explain the biochemical changes that occur in cataract formation. Among them are the oxidative damage by reactive oxygen species (ROS) and non-enzymatic glycosylation (Maillard reaction) of crystallins. The Maillard reaction, the reaction between amino groups on crystallins and sugars, proceeds through a condensation product, the Amadori product, which by subsequent reactions forms structurally diverse compounds that are collectively known as advanced glycation end products (AGEs). The presence of the Amadori product as well as specific AGEs have been established in the lens. Several recent studies have shown that glycated proteins can generate ROS. It is conceivable that glycated crystallins may function as a source of ROS in the lens and induce oxidative damage. During cataract formation, the lens glutathione level decreases significantly. This may lead to a decrease in the antioxidant potential and diminished activity of glyoxalase, that converts methylglyoxal (MG) to D-lactate. As a result, MG may accumulate and induce protein damage through AGE formation. MG can also arise from autoxidation of sugars and ascorbate. Significant amounts of MG are reported to be present in the human lens. The principal investigator has recently demonstrated that MG can rapidly react with lens crystallins to form AGEs that can crosslink proteins and generate fluorescent protein adducts. The principal investigator therefore hypothesizes that formation of ROS and AGEs by the Maillard reaction may cause collateral damage to lens crystallins in cataractogenesis. In this proposal, the principal investigator plans to test this hypothesis by in vitro and in vivo experiments. The major objectives include (1) demonstration of the formation of reactive oxygen species by glycated crystallins and determination of the factors which influence their formation; (2) determination of specific modifications and changes in physical parameters in crystallins by ROS generated from the Maillard reaction products; (3) determination of the effects of Maillard reaction-induced oxidative modifications on lens opacity and cataract formation in organ cultured lens and experimental animals and (4) determination of relationship(s) between MG-mediated Maillard reactions and oxidation in cataract formation using specific probes and a novel antibody. The experiments outlined in this proposal are expected to provide a better understanding of the mechanisms of lens protein modifications in cataract formation.

描述：已经提出了几种机制来解释 白内障形成过程中发生的生化变化。 其中有 活性氧 (ROS) 和非酶促氧化损伤 晶状体蛋白的糖基化（美拉德反应）。 美拉德反应， 晶状体蛋白上的氨基与糖之间的反应进行 通过缩合产物，Amadori 产物，随后 反应形成结构多样的化合物，这些化合物统称为 作为晚期糖基化终产物（AGE）。 阿马多里的存在 产品以及特定的 AGE 已在镜片中建立。 一些 最近的研究表明，糖化蛋白可以产生ROS。 这是 可以想象，糖化晶体蛋白可能作为 ROS 的来源。 晶状体并诱发氧化损伤。 白内障形成过程中，晶状体 谷胱甘肽水平显着降低。 这可能会导致减少 抗氧化潜力和乙二醛酶活性降低， 将甲基乙二醛 (MG) 转化为 D-乳酸。 结果，MG可能会累积 并通过 AGE 形成诱导蛋白质损伤。 MG 也可能源自 糖和抗坏血酸的自氧化。 大量的 MG 是 据报道存在于人类晶状体中。 主要研究者有 最近证明 MG 可以与晶状体蛋白快速反应 形成可以交联蛋白质并产生荧光蛋白的 AGE 加合物。 因此，主要研究者假设形成 美拉德反应产生的 ROS 和 AGE 可能会对晶状体造成附带损害 晶状体蛋白在白内障发生中的作用。 在这个提案中，校长 研究人员计划通过体外和体内测试这一假设 实验。 主要目标包括 (1) 展示 糖化晶状体蛋白形成活性氧 确定影响其形成的因素； (2) 确定物理参数的具体修改和变化 美拉德反应产物产生的 ROS 在晶状体蛋白中的作用； (3) 测定美拉德反应诱导的氧化作用 器官培养晶状体中晶状体混浊和白内障形成的改变 和实验动物以及（4）之间关系的确定 MG介导的美拉德反应和白内障形成中的氧化 特异性探针和新型抗体。 本文概述的实验 预计该提案将有助于更好地理解其机制 白内障形成中晶状体蛋白的修饰。