SYNTHETIC INHIBITORS OF MEMBRANE ANCHOR PHOSPHOLIPASES

在过去的四年里，越来越多的注意力集中在 细胞表面蛋白的不同类型的膜锚，糖基 磷脂酰肌醇(GPI)。在40多种GPI锚定蛋白中 到目前为止，鉴定出的是各种细胞表面抗原，肿瘤标志物， 受体系统、补体调节因子、细胞黏附分子 和细胞膜酶。生物合成、代谢与生物 糖脂锚定的功能正在积极研究中。这个 具有假定信号的表面蛋白和GPI组分的释放 GPI特异性磷脂酶C(GPI-PLC)和D的转导特性 (GPI-PLD)已经在几种寄生和哺乳动物细胞中被描述 系统。因此，及时需要特定的抑制剂和 这两种磷脂酶的生化探针有助于 许多重要的GPI锚定蛋白的生物学研究。我们的 初步数据显示，之前有一个独特的GPI成分 本实验室合成的化合物选择性抑制锥虫GPI- PLC，但不是PI-PLC，在1 mm的立体特定的无细胞系统中 举止。我们建议使用该组件的衍生品作为核心 保持GPI特异性并开发更有效的抑制剂的结构 GPI-PLC和哺乳动物GPI-PLD。各种取代的， 各自底物的不可切割和过渡态类似物 将被合成。活性缓蚀剂的最佳构象将 通过核磁共振、X-射线和计算机模拟等手段进行分析。相关光致活性 将为合作者准备生化探针以表征 这些酶的活性部位。特异性抑制剂对血管内皮细胞生长的影响 (1)GPI锚定蛋白的生物合成和代谢 布氏锥虫和溶组织内阿米巴，以及(2)信号 人淋巴细胞中白细胞介素2的转导过程也将是 与合作者一起进行调查，以开发潜力 抗寄生虫剂和新型免疫调节剂。

In the past four years increasing attention has been focused on a distinct type of membrane anchors of cell surface proteins, the glycosyl phosphatidylinositols (GPI). Among more than 40 of GPI-anchored proteins identified to date are various cell surface antigens, tumor markers, receptor systems, complement regulatory factors, cell adhesion molecules and membrane enzymes. The biosynthesis, metabolism and biological functions of glycolipid anchors are under active investigation. The release of surface proteins and GPI components with putative signal transduction properties by GPI-specific phospholipase C (GPI-PLC) and D (GPI-PLD) have been described in several parasitic and mammalian cell systems. Thus, there is a timely need for specific inhibitors and biochemical probes of these two phospholipases to facilitate the biological study of many important GPI-anchored proteins. Our preliminary data have shown that a unique GPI component previously synthesized in our laboratory selectively inhibit the trypanosome GPI- PLC, but not a PI-PLC, in a cell-free system at 1 mM in a stereospecific manner. We propose to use derivatives of this component as core structures to maintain GPI-specificity and develop more potent inhibitors of both GPI-PLC and a mammalian GPI-PLD. Various substituted, noncleavable and transition state analogs of the respective substrates will be synthesized. The optimal conformation of active inhibitors will be analyzed by NMR, X-ray and computer modeling. Related photoactivable biochemical probes will be prepared for a collaborator to characterize the active site of these enzymes. The effect of specific inhibitors on (1) the biosynthesis and metabolism of GPI-anchored proteins in Trypanosome brucei and Entamoeba histolytica, and (2) the signal transduction process of interleukins in human lymphocytes will also be investigated with collaborators towards the development of potential antiparasitic agents and novel immunomodulators.