STRUCTURAL BIOLOGY OF PROSTAGLANDIN BIOSYNTHESIS

前列腺素H合酶（PGHS）是一种膜蛋白， 将花生四烯酸（一种必需脂肪酸）转化为 通过自由基机制的酶产物，PGG 2和PGH 2。 前列腺素引发许多细胞和组织反应，包括 血管舒张、血管收缩、血液凝固、细胞增殖和 炎症 非甾体抗炎药（NSAID），抑制 通过靶向PGHS的环氧合酶活性的前列腺素类生物合成， 用于治疗炎症和心血管疾病的某些症状 疾病 前列腺素类还参与许多疾病的病理生理学， 包括动脉粥样硬化、类风湿性关节炎和癌症在内的疾病; 阿司匹林现在已被证明是一种抗癌预防剂。 两种同种型 已发现PGHS的：PGHS-1参与体内平衡或“房子- 细胞因子诱导PGHS-2合成的同时， 在炎症事件中。 我们正在继续努力确定的X射线晶体结构的 PGHS-1的最高分辨率。 我们已经解决了 PGHS-1至3.1 A分辨率，已经建立了酶的原子模型， 已经表征了PGHS-1与四种NSAID的复合物：溴阿司匹林， 氟比洛芬、碘舒洛芬和碘吲哚美辛。 我们开始 在同步辐射下收集高分辨率数据（2.8 A） 需要进一步技术发展的设施，如 膜蛋白晶体的快速冷冻。 我们会继续研究 酶-药物相互作用和结构-功能的本质 的关系，特别侧重于底物和 NSAID相互作用以及靶向ER膜的模式。 这 将涉及分析PGHS-1中配体诱导的构象变化， 并通过一种方法表征PGHS-1和PGHS-2的配体络合物， 酶学，EPR/ENDOR光谱和X射线的补充系列 衍射实验 随着PGHS诱导型的发现， 关于PGHS-1和PGHS-2之间的功能差异的问题出现了。 利用已知序列预测了PGHS-2的结构， PGHS-1作为模型，并分析结构-功能 这种新的同工酶的关系。 小鼠PGHS-2的结晶试验 正在进行中

Prostaglandin H synthase (PGHS) is a an integral membrane protein which converts arachidonic acid, an essential fatty acid, into the initial enzymatic products, PGG2 and PGH2 by means of a free radical mechanism. Prostaglandins initiate numerous cell and tissue responses including vasodilation, vaso-constriction, blood clotting, cell proliferation and inflammation. Nonsteroidal anti-inflammatory drugs (NSAIDs), which inhibit prostanoid biosynthesis by targeting the cyclooxygenase activity of PGHS, are used to treat certain symptoms of inflammatory and cardiovascular diseases. The prostanoids are also involved in pathophysiology of a number of diseases including atherosclerosis, rheumatoid arthritis, and cancer; in the latter, aspirin is now a proven anticancer prophylaxis. Two isoforms of PGHS have been discovered: PGHS-1 is involved in homeostatic or "house- keeping" prostaglandin biosynthesis while PGHS-2 induced by cytokines during inflammatory events. We are continuing our efforts to determine the X-ray crystal structure of PGHS-1 to the highest resolution possible. We have solved the structure of PGHS-1 to 3.1 A resolution, have built an atomic model of the enzyme, and have characterized PGHS-1 complexes a=with four NSAIDs: bromoaspirin, flurbiprofen, iodosuprofen and iodoindomethacin. We are beginning to collect high resolution data (2.8 A) at the synchrotron radiation facilities which will require further technological development such as the flash-freezing of membrane protein crystals. We will continue our study on the nature of enzyme-drug interactions and structure-function relationships, with particular focus on the mechanisms of substrate and NSAID interactions as well as the mode of targeting the ER membrane. This would involve analyzing ligand-induced conformational changes in PGHS-1, and characterizing ligand complexes of PGHS-1 and PGHS-2 by means of a complementary series of enzymological, EPR/ENDOR spectroscopic and X-ray diffraction experiments. With the discovery of an inducible from of PGHS, questions arise about the functional differences between PGHS-1 and PGHS-2. We have predicted the structure of PGHS-2, using the known sequences and the PGHS-1 as a model, and are analyzing the structure-function relationships in this new isozyme. Crystallization trial for mouse PGHS-2 are underway.