ARYL AND ALCOHOL SULFOTRANSFERASES IN DRUG METABOLISM

描述(改编自申请人的摘要)：苄基的硫酸盐化 醇、烯丙醇和N-羟基芳胺通常是关键步骤 在它们的生物转化为化学反应代谢物的过程中 与细胞大分子的共价键，导致 各种毒理学反应，包括细胞坏死、突变和 致癌。这项研究的长期目标是更全面地了解 并预测芳基和醇硫转移酶在这些过程中的作用 有毒反应。本申请中提出的研究解决了 底物和缓蚀剂分子识别的基本问题 以及肝内芳基磺基转移酶IV(AST IV)和 乙醇(羟基类固醇)磺基转移酶(STA)。的具体目标1和2 提案涉及开发和改进三维模型 天冬氨酸转氨酶IV和天冬氨酸转氨酶的构效关系。Aim 1基于 假设硫酰受体位置上有特定的氨基酸残基 这些酶是分子识别的主要决定因素 这些酶对底物和抑制剂的立体选择性。这 假设将使用多方面的方法进行检验，其中动力学 立体化学定义的底物的分析与定点定向相结合 基于突变、蛋白质同源建模和构象建模分析 关于结构对齐。关于立体化学方面的研究 α-羟基三苯氧胺的硫化反应(可能是 在接受这种药物治疗的一小部分女性身上看到的致癌作用 药物)和几个相关的模型烯丙醇也将继续。目标2 的C-末端区域的同源模型的精细化。 AST IV和StA。在第三个具体目标中，同调模型和 将利用三维结构-活性关系进行设计， 合成并评价大鼠AST IV和STA的异构体特异性抑制物。 这些针对异构体特异性抑制剂的研究结果将被推广。 与相关的人类芳基和醇磺基转移酶的亚型有关。最后， 该提案的具体目标4是探索AST的表达和活性 胆管细胞(胆管上皮细胞)和枯否细胞内的IV和STA 细胞，两种类型的非实质细胞，在 肝脏的病理生理学。建议的结果将于 因此，这笔赠款的继续将提供重要的新见解 转化为底物和抑制剂的分子识别等因素 肝内定位，调节芳香和酒精 磺基转移酶介导的异生和内生代谢及其作用 肝脏病理生理学。

DESCRIPTION (Adapted from the applicant's abstract): The sulfation of benzylic alcohols, allylic alcohols, and N-hydroxy arylamines is often the critical step in their biotransformation into chemically reactive metabolites that can form covalent bonds with cellular macromolecules, the initial step leading to various toxicological responses including cellular necrosis, mutagenesis, and carcinogenesis. The long-term goal of this research is to more fully understand and predict the roles that aryl and alcohol sulfotransferases play in these toxic responses. The research proposed in this application addresses fundamental aspects of the molecular recognition of substrates and inhibitors as well as intrahepatic expression of aryl sulfotranferase IV (AST IV) and alcohol (hydroxysteroid) sulfotransferase (STa). Specific Aims 1 and 2 of the proposal involve the development and refinement of three-dimensional models of structure-activity relationships for AST IV and STa. Aim 1 is based on the hypothesis that specific amino acid residues lining the sulfuryl acceptor sites of these enzymes are major determinants of the molecular recognition and stereoselectivity of these enzymes for substrates and inhibitors. This hypothesis will be tested using a multi-faceted approach wherein kinetic analyses of stereochemically defined substrates are coupled with site-directed mutagenesis, protein homology modeling, and conformer modeling analysis based on structure-alignment. Investigations on stereochemical aspects of the sulfation of alpha-hydroxytamoxifen (a potentially critical step involved in the carcinogenic effects seen in a small percentage of women treated with this drug) and several related model allylic alcohols will also be continued. Aim 2 is centered on refinement of the homology models from the C-terminal regions of AST IV and STa. In the third specific aim, homology models and three-dimensional structure-activity relationships will be utilized to design, synthesize, and evaluate isoform-specific inhibitors of rat AST IV and STa. Results from these studies on isoform-specific inhibitors will then be extended to the related human isoforms of aryl and alcohol sulfotransferases. Finally, Specific Aim 4 of the proposal is to explore the expression and activity of AST IV and STa within both cholangiocytes (bile duct epithelial cells) and Kupffer cells, two types of nonparenchymal cells that play critical roles in the pathophysiology of the liver. The results to be forthcoming from the proposed continuation of this grant will, therefore, provide significant new insight into factors, such as molecular recognition of substrates and inhibitors and intrahepatic localizations, that regulate aryl and alcohol sulfotransferase-mediated xenobiotic and endobiotic metabolism and their roles in liver pathophysiology.