SUICIDE INACTIVATION OF LTA4 HYDROLASE AND THROMBOXANE SYNTHASE

LTA4 水解酶和血栓烷合酶的自杀失活

• 批准号: 3758458
• 负责人: FRANK A FITZPATRICK
• 金额: --
• 依托单位: NATIONAL JEWISH HEALTH
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/3758458
• 关键词: eicosanoids; enzyme mechanism; fatty acid biosynthesis; guinea pigs; hydrolase; immunochemistry; laboratory rabbit; lung disorder; molecular biology; pneumonia; stoichiometry; thromboxanes

Eicosanoids are biologically active lipids derived from cellular oxidative metabolism of arachidonic acid. These substances are autacoid mediators which initiate, aggravate, or sustain respiratory and cardiac disorders. Recent investigations indicate that 'suicide' inactivation of certain key enzymes occurs during eicosanoid biosynthesis. Suicide inactivation, by modulating the accumulation and disposition of pivotal substrates, influences both quantitative and qualitative aspects of eicosanoid formation. For example, termination of leukotriene B4 biosynthesis by suicide inactivation of LTA4 hydrolase may promote conversion of LTA4 into other leukotrienes; it may promote non-enzymatic reactions of LTA4, such as hydrolysis or nucleophilic addition to macromolecules; or it may promote secretion of LTA4 by one cell type for metabolism by a separate cell type (transcellular biosynthesis). An analogous example exists for thromboxane A4 biosynthesis. Suicide inactivation of thromboxane synthase terminates thromboxane biosynthesis and promotes alternate fates for its pivotal substrate, prostaglandin endoperoxide (PGH2). These include conversion into other prostaglandins by non-enzymatic processes, or by transcellular biosynthesis. We propose to investigate: i) the chemical nature of the suicide inactivation process ii) its biochemical and cellular consequences with particular reference to the accumulation and disposition of LTA4 and PGH2 iii) the selectivity, reversibility, and potential to use suicide inactivation as a "marker" for unrestrained eicosanoid biosynthesis. We selected LTA4 hydrolase and thromboxane A2 synthase as enzymatic models because they regulate critical branch points during eicosanoid biosynthesis. The former influences leukotriene formation and the latter influences prostaglandin and thromboxane formation. In addition, their products, leukotriene B4 and thromboxane A2, have potent effects on pulmonary vasoconstriction and blood cell activation. This is a new research program based on the hypothesis that suicide substrate inactivation of enzymes in the arachidonic acid cascade is a cellular mechanism to alter temporally, qualitatively, and quantitatively the biosynthesis of eicosanoids. We aim to develop a more accurate model to account for the role of eicosanoids in chronic, rather than acute, pulmonary disorders.

类二十烷酸是源自细胞氧化的具有生物活性的脂质 花生四烯酸的代谢。 这些物质是自体介质 引发、加重或维持呼吸系统和心脏疾病。 最近的调查表明，某些关键的“自杀”失活 类二十烷酸生物合成过程中会产生酶。 自杀失活，通过 调节关键底物的积累和处置， 影响类二十烷酸的定量和定性 形成。 例如，通过以下方式终止白三烯 B4 生物合成： LTA4水解酶的自杀失活可能促进LTA4转化为 其他白三烯；它可能促进LTA4的非酶促反应，例如 大分子的水解或亲核加成；或者它可能会促进 一种细胞类型分泌 LTA4，供另一种细胞类型代谢 （跨细胞生物合成）。 血栓素也有类似的例子 A4生物合成。 血栓素合酶的自杀失活终止 血栓素生物合成并促进其关键的交替命运 底物，前列腺素内过氧化物（PGH2）。 这些包括转换 通过非酶促过程或通过跨细胞转化为其他前列腺素 生物合成。 我们建议调查：i) 自杀的化学性质 灭活过程 ii) 其生化和细胞后果 特别参考 LTA4 和 PGH2 的积累和处置 iii) 选择性、可逆性和自杀的可能性 失活作为不受限制的类二十烷酸生物合成的“标记”。 我们 选择LTA4水解酶和血栓素A2合酶作为酶模型 因为它们在类二十烷酸期间调节关键分支点 生物合成。 前者影响白三烯的形成，后者影响 影响前列腺素和血栓素的形成。 此外，他们的 产品白三烯 B4 和血栓素 A2 对 肺血管收缩和血细胞活化。 这是一项新的研究计划，基于自杀的假设 花生四烯酸级联中酶的底物失活是 时间、质量和数量改变的细胞机制 类二十烷酸的生物合成。 我们的目标是开发更准确的模型 解释类二十烷酸在慢性而非急性中的作用， 肺部疾病。