Biochemical Studies of 14 kDa Phospholipases A2

描述：（由申请人提供）磷脂酶A2（PLA 2s）催化 水解膜磷脂的sn-2酯以产生游离脂肪酸 酸和溶血磷脂。对这些问题的兴趣很大， 酶，因为它们在花生四烯酸的释放中的作用， 哺乳动物细胞膜用于类花生酸介质的生物合成 炎症（白藜芦醇、白三烯等）。还有 相当大的兴趣，这些酶作为一个范例，了解 界面酶学（酶在脂-水界面的作用）。 细胞中的许多酶在膜上起作用。哺乳动物细胞包含两种类型 参与花生四烯酸生产的PLA 2。分泌的PLA 2 （sPLA 2）是14-18 kDa的钙依赖性酶，由细胞分泌， 大量哺乳动物细胞在用促炎剂刺激后 调解员哺乳动物细胞还含有87-kDA胞质PLA 2（cPLA 2）， 响应胞质钙升高而转移到膜上。 最近，我们克隆了几个新的小鼠和人sPLA 2。因此，现在 很明显，sPLA 2在哺乳动物中构成了一个蛋白质超家族。我们有 在生产重组形式的 全套小鼠和人sPLA 2。我们将完成这一进程， 研究这些酶的界面动力学和结合特性。 我们现在面临的任务是确定这些基因的表达谱， 哺乳动物细胞中的sPLA 2，我们的研究将集中在气道细胞 正常人和哮喘患者的情况。众所周知，类二十烷酸起着 在引起许多与哮喘相关的症状方面起着重要作用。是 重要的是确定哪些PLA 2参与释放花生四烯酸。 这些信息将有助于设计新一代的治疗方法 用于治疗气道炎性疾病。一旦我们确定了 PLA 2在人气道细胞中表达，我们将使用PLA 2特异性 抗体和小分子量抑制剂来探测这些酶是否 参与花生四烯酸的释放 PLA 2在哺乳动物细胞中释放花生四烯酸的机制 酸是部分理解的。一些sPLA 2细胞外作用于血浆 细胞膜，而另一些则内化为点状细胞内 膜隔室对于后一种情况，定义这一点很重要 更详细地了解膜隔室，并确定酶在何处起作用， 释放花生四烯酸。这些研究将有助于我们的基本 了解哺乳动物细胞如何启动类花生酸级联反应。

DESCRIPTION: (provided by applicant) Phospholipases A2 (PLA2s) catalyze the hydrolysis of the sn-2 ester of membrane phospholipids to produce a free fatty acid and a lysophospholipid. There has been considerable interest in these enzymes because of their role in the liberation of arachidonic acid from mammalian cell membranes for the biosynthesis of the eicosanoid mediators of inflammation (prostaglandins, leukotrienes, and others). There is also considerable interest in these enzymes as a paradigm for understanding interfacial enzymology (the action of enzymes at the lipid-water interface). Many enzymes in cells operate on membranes. Mammalian cells contain two types of PLA2s that are involved in arachidonic acid production. The secreted PLA2s (sPLA2s) are 14-18 kDa, calcium-dependent enzymes that are secreted from a large number of mammalian cells following stimulation with pro-inflammatory mediators. Mammalian cells also contain an 87-kDA cytosolic PLA2 (cPLA2) that translocates to the membrane in response to a rise in cytosolic calcium. Recently we have cloned several new mouse and human sPLA2s. Thus, it is now clear that the sPLA2s constitute a superfamily of proteins in mammals. We have made significant progress toward the production of recombinant forms of the full set of mouse and human sPLA2s. We will complete this process and also study the interfacial kinetic and binding properties of these enzymes. We are now faced with the task of determining the expression profile of these sPLA2s in mammalian cells, and our studies will focus on cells from the airways of normal and asthmatic patients. It is well established that eicosanoids play a prominent role in causing many of the symptoms associated with asthma. It is important to determine which PLA2s are involved in releasing arachidonic acid. Such information will be useful in designing a new generation of therapeutics for treatment of airway inflammatory disorders. Once we have identified the PLA2s that are expressed in human airway cells, we will use PLA2-specific antibodies and small molecular weight inhibitors to probe whether these enzymes are involved in arachidonic acid release. The mechanisms by which PLA2s act in mammalian cells to liberate arachidonic acid are partially understood. Some sPLA2s act extracellularly on the plasma membrane of cells, while others are internalized into punctate intracellular membrane compartments. For the latter case, it is important to define this membrane compartment in more detail and to determine where the enzyme acts to release arachidonic acid. These studies will contribute to our fundamental understanding of how mammalian cells initiate the eicosanoid cascade.