STRUCTURE AND INTERFACIAL FUNCTION OF PLATELET ACTIVATING FACTOR ACETYLHYDROLASE

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 脂代谢是人类健康的一个主要问题，主要关注与低密度脂蛋白和高密度脂蛋白有关的炎症反应和脂类稳态。许多与低密度脂蛋白和高密度脂蛋白颗粒相关的蛋白质在这些脂质途径中起着关键作用。血浆形式的血小板激活因子乙酰水解酶(PPAFAH)通过降低信号分子血小板激活因子(PAF)作为一般抗炎清除剂的水平在低密度脂蛋白颗粒表面发挥作用，并与过敏性休克、哮喘和过敏反应有关。作为一种未知同源的低密度脂蛋白相关蛋白，pPAFAH是一个有价值的结构靶点。除了降低PAF水平的作用外，它还与其他促炎剂的水解性有关，如低密度脂蛋白颗粒的氧化脂质。对pPAFAH催化的生理反应的分子理解需要酶与其底物PAF和氧化磷脂相互作用的结构模型。我们将通过4个具体目标来阐明PPAFAH的结构与界面酶功能之间的关系：(1)解决PPAFAH的高分辨晶体结构。将探索洗涤剂和两亲性分子的使用，以提供更高分辨率的结构，以及功能更相关的结构。(Ii)将通过结构和动力学表征来探索和开发pPAFAH的抑制剂，以阐明体内的生理功能。(3)结合结构和界面动力学研究，进一步阐明pPAFAH的生理作用。来自抑制和结构研究的见解将有助于开发该酶的原子拆分机制。酶-配体复合体将被用来进一步阐明酶的机制。(Iv)探讨对苯丙烷烃与有机磷(OP)化合物在生理上的相关反应，包括使用低密度脂蛋白相关酶作为OP神经毒素的生物清除靶标的可能性。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Lipid metabolism is a major human health concern, with much attention focused on inflammation and lipid homeostatis of lipids linked to low and high density lipoprotein (LDL, HDL). Many proteins that are associated with LDL and HDL particles play a critical role in these lipid pathways. The plasma form of platelet activating factor acetylhydrolase (pPAFAH) functions on the surface of LDL particles by reducing levels of the signaling molecule platelet activating factor (PAF) as a general anti-inflammatory scavenger, and is linked to anaphylactic shock, asthma and allergic reactions. As a LDL-associated protein with no known homologues, pPAFAH is a worthy structural target. In addition to its role to reduce PAF levels, it has also been implicated in hydrolytic activities of other pro-inflammatory agents, such as oxidized lipids of LDL particles. A molecular understanding of the physiological reactions catalyzed by pPAFAH requires structural models of the enzyme interacting with its substrates PAF and oxidized phospholipids. We will elucidate the relationship between structure and interfacial enzyme function for pPAFAH via 4 specific aims: (i) The high-resolution crystal structure of pPAFAH will be solved. The use of detergents and amphiphilic molecules will be explored to provide higher resolution structures, as well as functionally more relevant structures. (ii) Inhibitors of pPAFAH will be explored and developed via structural and kinetic characterization to elucidate in vivo physiological functions. (iii) Combining structure with interfacial kinetic studies, we will further elucidate the physiological roles of pPAFAH. Insights from inhibition and structural studies will help develop an atomic resolution mechanism of the enzyme. Enzyme-ligand complexes will be pursued that further elucidate the enzyme mechanism. (iv) The physiologically relevant reaction of pPAFAH with organophosphate (OP) compounds will be explored, including the possible use of the LDL-associated enzyme as a bioscavenger target of OP neurotoxins.