STRUCTURE/FUNCTION OF PROSTAGLANDIN H SYNTHASE 2

前列腺素H合成酶(PGHS)催化环氧合酶活性 前列腺素生物合成的第一个关键步骤是 一组有效的生物活性脂类被认为在许多 病理生理过程，包括炎症、血管、胃 以及肾功能、生殖和肿瘤发生。两种PGHS亚型是 已知：PGHS-1被认为是结构性的，被归因于管家 功能：在涉及的许多细胞中，PGHS-2可被细胞因子强烈诱导 在炎症和增殖过程中。除了对PGHS的控制外- 1和-2基因表达，细胞前列腺素合成也密切相关 在环氧合酶催化水平上进行调节，使用不同的催化 控制两种PGHS亚型。PGHS-2环氧合酶有很多 过氧化氢激活剂的需求量低于PGHS-1环氧合酶。 产品在反馈激活方面的这种差异提供了一个简单的 环氧合酶差异性细胞调控的生化基础 催化作用。细胞环氧合酶的催化也会受到脂肪的限制。 酸性底物的可用性。PGHS-1环氧合酶活性显示 低花生四烯酸水平下的合作行为，而PGHS-2 酶遵循简单的饱和动力学。这个项目的总体目标是 是为了了解PGHS亚型对催化作用的调节 分子水平。动力学、光谱和结构研究将是 与两种PGHS亚型和靶向突变蛋白一起进行 实现以下具体目标：1)确定机制基础 对于PGHS-1和PGHS-2中不同的过氧化氢活化剂要求， 并探讨阿司匹林对PGHS-2作用机制的改变；2) 确定控制过氧化氢活化剂的结构元素(S) 在PGHS-1和-2中的要求，并调查 阿司匹林治疗的PGHS-2；2)确定控制的结构元件(S) 两种异构体所需的过氧化氢活化剂；以及3) 评估脂肪酸和过氧化氢之间的相互依赖关系 环氧合酶对两种PGHS亚型的催化控制。

The cyclooxygenase activity of prostaglandin H synthase (PGHS) catalyzes the first committed step in the biosynthesis of the prostaglandins, a group of potent, bioactive lipids believed important in many pathophysiological processes, including inflammation, vascular, gastric and renal function, reproduction, and tumorigenesis. Two PGHS isoforms are known: PGHS-1 is regarded as constitutive and is ascribed housekeeping function; PGHS 2 is strongly inducible by cytokines in many cells involved in inflammatory and proliferative processes. Besides the controls of PGHS- 1 and -2 gene expression, cellular prostaglandin synthesis is also tightly regulated at the cyclooxygenase catalytic level, with different catalytic controls for the two PGHS isoforms. PGHS-2 cyclooxygenase has a much lower hydroperoxide activator requirement than the PGHS-1 cyclooxygenase. This difference in feedback activation by the product provides a simple biochemical basis for differential cellular control of cyclooxygenase catalysis. Cellular cyclooxygenase catalysis also can be limited by fatty acid substrate availability. PGHS-1 cyclooxygenase activity exhibits cooperative behavior at low arachidonic acid levels, whereas the PGHS-2 enzyme follows simple saturable kinetics. The general goal of this project is to understand the regulation of catalysis by the PGHS isoforms at a molecular level. Kinetic, spectroscopic, and structural studies will be undertaken with the two PGHS isoforms and targeted mutant proteins to achieve the following specific aims: 1) Identify the mechanistic basis(es) for the different hydroperoxide activator requirements in PGHS-1 and -2, and investigate the mechanistic changes in aspirin-treated PGHS-2; 2) Identify the structural element(s) controlling the hydroperoxide activator requirements in PGHS-1 and -2, and investigate the mechanistic changes in aspirin-treated PGHS-2; 2) Identify the structural element(s) controlling the hydroperoxide activator requirements in the two isoforms; and 3) Evaluate the interdependence between fatty acid and peroxide in cyclooxygenase catalytic control for the two PGHS isoforms.