The leukotrienes (LT) are products of the 5-lipoxygenase pathway of arachidonic acid metabolism which have been implicated to play an important role in the pathogenesis of asthma and other allergic diseases, and in inflammatory diseases such as rheumatoid arthritis. The sulfidopeptide leukotrienes, LTC4 and LTD4, mediate their pathobiological action by constriction of bronchial and other smooth muscle. LTE4 and also LTC4 and LTD4 increase vascular permeability. LTB4 is chemotactic for polymorphonuclear leukocytes (PMN) and causes superoxide production and lysosomal granule release from these cells. The goal of this proposal is to understand the biochemical and biological mechanisms which control the production, metabolism, and cellular function of the leukotrienes. The first specific aim of this proposal will be to understand the controls of the biosynthesis of LTC4, and the regulation of LTD4 receptor function. We will employ both fast protein liquid chromatography and affinity chromatography to purify the LTC4 synthase from human lung and then study its control and subunit composition. We will synthesize specific inhibitors of this enzyme which will be used for the affinity chromatography. We will use cultured human eosinophils to study the mechanism by which biosynthesized LTC4 is exported from these cells. Specifically designed agonists and antagonists of LTD4 receptor function and binding will be prepared. The second specific aim will be to determine the controls and mechanism of lipoxygenation by 5- and 15- lipoxygenase utilizing artificial membrane systems and specifically synthesized substrates and enzyme inhibitors. The third specific goal will be to study the metabolism of LTB4 using high pressure oxygen techniques and to synthesize specific antagonists of LTB4 for use in both receptor binding and metabolic studies.
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