天然酚类化合物调节COX酶催化活性的分子机理研究

Cyclooxygenase (COX) 1 and 2 catalyze the metabolism of arachidonic acid (AA), resulting in the formation of important biological mediators called prostanoids, which include prostaglandins(PGs), prostacyclins, and thromboxanes. Because abnormally-elevated levels of these autacoidsplay an important role in mediating inflammation, pharmacological inhibition of COX 1 and/or 2 catalytic activity is well known to be effective in the treatment of various inflammatory conditions. On the other hand, normal levels of these autacoids formed by constitutively-expressed COX enzymes (mostly COX 1) are required for maintaining normal physiological functions of the body. Phenolic compounds are among the most abundant naturally-occurring chemicals present in our diet. Studies have shown that the dietary phenolics exert many important biological functions, such as anti-inflammation, cancer chemoprevention, and cardiovascular protection. However, the mechanisms underlying many of their important biological effects are still poorly understood. Our recent studies showed that some of the dietary phenolics can activate the catalytic activity of COX 1 and 2 by serving as co-factors (effective at nM concentrations in vitro and in vivo), resulting in increased biosynthesis of certain PGs. The proposed studies seek to systematically test the mechanistic hypothesis that while some of the dietary polyphenols are physiological cofactors of COX 1 and 2 in vivo. To achieve our scientific goals, we will pursue the following three goals: 1. Determine the direct stimulatory effectof a large number of selected phenolic compounds on COX 1/2-mediated prostanoid synthesis in cultured cells. 2. Use computational molecular modeling approach coupled with site-directed mutagenesis and biochemical enzyme kinetics to determine the molecular mechanism and structural basis by which certain phenolic compounds activate the COX 1/2 catalytic activity. 3. Use animal models to verify that activation of COX 1/2-mediated PG biosynthesis by certain phenolic compounds do occur in vivo and will modulate pathological processes.

食物中多酚类化合物含量丰富且具有重要的生物学功能。我们近期的研究显示有些食源多酚类物质能作为生理辅酶因子来激活环氧化酶1和2 (COX1/2)的催化活性（有效浓度在nM水平），导致前列腺素（PG）类物质合成的增加。因此，我们提出了关于它们作用机理的一个新假说，即：这些化合物在体内能作为COX酶的辅酶因子以维持其催化稳定性及活性，进而维持体内PG类活性物质的正常合成和生理功能。本研究项目旨在于用实验手段来系统性地验证这个新假说。具体有三个目标：1．选择性表达人COX1或COX2酶的离体细胞培养模型来检测已筛选出来的天然酚类化合物对COX1/2所催化形成的PG类活性物质的激活作用。2．联合运用分子模型研究方法、蛋白定点突变方法及酶生化动力学方法来确定这些酚类化合物激活COX1/2酶催化活性的分子机理及结构基础。3．用动物模型来验证这些酚类化合物对PG类活性物质介导的某些病理过程的调节作用。

食物中多酚类化合物含量丰富且具有重要的生物学功能。我们近期的研究显示有些食源多酚类物质能作为生理辅酶因子来激活环氧化酶 1 和 2 (COX-1/2) 的催化活性（有效浓度在 nM 水平），导致前列腺素（PG）类物质合成的增加。因此，我们提出了关于它们作用机理的一个新假说，即：这些化合物在体内能作为 COX 酶的辅酶因子以维持其催化稳定性及活性，进而维持体内 PG 类活性物质的正常合成和生理功能。本研究项目旨在于用实验手段来系统性地验证这个新假说。具体有三个目标：1．选择性表达人 COX-1 或 COX-2 酶的离体细胞培养模型来检测已筛选出来的天然酚类化合物对 COX-1/2 所催化形成的 PG 类活性物质的激活作用。2．联合运用分子模型研究方法、蛋白定点突变方法及酶生化动力学方法来确定这些酚类化合物激活 COX-1/2 酶催化活性的分子机理及结构基础。3．用动物模型来验证这些酚类化合物对 PG 类活性物质介导的某些病理过程的调节作用。

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