PROSTAGLANDIN SYNTHASE--STRUCTURE AND FUNCTION

类二十烷酸，一组氧化衍生物， 多不饱和脂肪酸，已被赋予重要的作用， 各种生理和病理过程 包括炎症，免疫监视，睡眠诱导， 中风、心肌梗塞、激素释放和致癌作用。 每一种生物合成的第一个关键步骤是 类二十烷酸，分子氧结合到脂肪酸中， 脂肪酸是由脂肪酸加氧酶催化的。 最突出的 哺乳动物脂肪酸加氧酶是环氧化酶的活性， 前列腺素H合酶，其产物随后转化为 转化为前列腺素血栓素和前列环素 两个重要 环氧合酶产生前列腺素的特性 是反应速率的反馈放大，由 产物氢过氧化物和自催化失活。 这些 这些特征为其它脂肪酸加氧酶所共有， 在类花生酸生物合成的调节中是重要的。 前列腺素H合酶可以以足够的量分离， 详细的物理特性，目前是更多 比其他哺乳动物脂肪酸加氧酶更便于研究。 总的目标是将催化和调节行为联系起来 的合成酶的反应机制，并对结构 合成酶蛋白和天然膜环境。 的 具体目的是分析纯绵羊合酶，以：a） 表征过氧化物酶活性还 存在于合成酶中的蛋白质增强了合成酶的反应动力学。 环氧合酶：（B）阐明自催化的机制 失活所述合酶;以及c）表征所述功能性的 合成酶的结构域负责与 活化剂、底物、抑制剂和磷脂。 使用的方法包括：环氧化酶分析 和过氧化物酶活性，以及这些的计算机模拟 活性;蛋白质和多肽纯化， 表征;紫外-可见分光光度法;圆二色性和 磁性圆二色性;和电子顺磁共振。

The eicosanoids, a collection of oxygenated derivatives of polyunsaturated fatty acids, have been ascribed important roles in a broad variety of physiological and pathological processes including inflammation, immune surveillance, sleep induction, stroke, myocardial infarction, hormone release, and carcinogenesis. The first committed step in the biosynthesis of each of the eicosanoids, the incorporation of molecular oxygen into a fatty acid, is catalyzed by a fatty acid oxygenase. The most prominent mammalian fatty acid oxygenase is the cyclookygenase activity of prostaglandin H synthase, whose product is subsequently converted into prostaglandins, thromboxanes and prostacyclins. Two important characteristics of prostaglandin generation by the cyclooxygenase are the feedback amplification of the reaction rate, mediated by product hydroperoxide, and the self-catalyzed inactivation. These characteristics are shared by other fatty acid oxygenases and may be important in regulation of eicosanoid biosynthesis. Prostaglandin H synthase can be isolated in quantities sufficient for detailed physical characterization and currently is more convenient to study than other mammalian fatty acid oxygenases. The overall goal is to relate the catalytic and regulatory behavior of the synthase to its reaction mechanism, and to the structure of the synthase protein and the native membrane environment. The specific aims are to analyze the pure ovine synthase to: a) characterize the mechanism by which the peroxidase activity also present in the synthase enhances the reaction dynamics of the cyclooxygenase: (b) elucidate the mechanisms for self-catalyzed inactivation of the synthase; and c) characterize the functional domains of the synthase responsible for its interactions with activators, substrates, inhibitors, and phospholipid. The methodologies to be used include: analysis of cyclooxygenase and peroxidase activities, and computer simulation of these activities; protein and polypeptide purification and characterization; UV-vis spectrophotometry; circuLar dichroism and magnetic circular dichroism; and electron paramagnetic resonance.