FREE RADICAL ENZYME DAMAGE-- AN ALZHEIMER'S DISEASE MODEL

自由基酶损伤——阿尔茨海默病模型

• 批准号: 3803012
• 负责人: STANLEY NELSON
• 金额: --
• 依托单位: UNIVERSITY OF KANSAS MEDICAL CENTER
• 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/3803012
• 关键词: Alzheimer's disease; aluminum; antioxidants; ascorbate; brain metabolism; cytotoxicity; disease /disorder model; enzyme inhibitors; ferritin; fluorimetry; free radical oxygen; hemoprotein; iron; iron metabolism; lactate dehydrogenases; lead; oxidation; transferrin

Elevated brain levels of iron and aluminum in patients with Alzheimer's disease suggest that these metals play a role in the disease process. One mechanism for this action is in the production of reactive oxygen species (ROS), or oxygen free radicals. If the production of ROS exceeds the cellular protective mechanisms, ROS will destructively oxidize many cell constituents, including enzymes. The proposed work will focus on the effect of ROS on an important metabolic enzyme in brain energy metabolism, lactate dehydrogenase (LDH). We found in some preliminary experiments that ascorbate plus iron inactivates LDH in a way that suggests ROS are involved. The experimental model to be used for studying enzyme inactivation in iron systems is an in vitro model; LDH is incubated with iron and ascorbate and the decrease in LDH activity is a measure of chemical damage to the enzyme. Ascorbate can be a protective antioxidant, but under some conditions it can contribute to oxidative damage by way of Fe3+ reduction to Fe2+. Fe2+ can act in two ways to catalyze the production of ROS; 1) it can react with O2 to form superoxide radical, and 2) it can react with hydrogen peroxide to produce the highly reactive hydroxyl radical. The specific aims are: 1) To know whether or not the iron/ascorbate inactivation of lactate dehydrogenase (LDH) is largely the result of reactive oxygen species, and if so, which species are involved. 2) To know the ascorbate/iron concentration relationships that cause greatest enzyme inactivation. 3) To find if protein-bound iron, in addition to iron salts, can produce enzyme inactivation in the presence of ascorbate. The protein-bound forms to be studied are human heme protein, transferrin and ferritin. 4) To determine if the addition of aluminum or lead salts to the ascorbate/iron/LDH system potentiates LDH inactivation.

阿尔茨海默病患者脑内铁和铝水平升高 疾病表明，这些金属在疾病过程中发挥作用。 一 这种作用的机制是产生活性氧 (ROS)或氧自由基。 如果ROS的产生超过了 细胞保护机制，ROS会破坏性地氧化许多细胞 成分，包括酶。 拟议的工作将侧重于 ROS对脑能量代谢中重要代谢酶的影响， 乳酸脱氢酶（LDH）。 我们在一些初步实验中发现， 抗坏血酸加铁灭活LDH的方式表明ROS是 涉案 研究酶的实验模型 铁系统中的失活是一种体外模型;将LDH与 铁和抗坏血酸，LDH活性的降低是衡量 对酶的化学损伤。 抗坏血酸可以是一种保护性抗氧化剂， 但在某些情况下，它可以通过以下方式促进氧化损伤： Fe 3+还原为Fe 2+。 Fe 2+可以通过两种方式催化 ROS的产生：1）它能与O2反应形成超氧自由基， 2)它可以与过氧化氢反应， 羟基自由基 具体目标是： 1)为了了解铁/抗坏血酸盐灭活乳酸是否 脱氢酶（LDH）主要是活性氧物质的结果， 如果是，涉及哪些物种。 2)了解抗坏血酸/铁浓度的关系， 最大的酶失活。 3)为了发现蛋白质结合铁，除了铁盐，是否可以产生 在抗坏血酸存在下的酶失活。 蛋白质结合形式 待研究的是人血红素蛋白、转铁蛋白和铁蛋白。 4)为了确定是否将铝盐或铅盐添加到 抗坏血酸/铁/LDH系统增强LDH失活。