ARYL SULFOTRANSFERASE IN DRUG AND XENOBIOTIC METABOLISM

芳基异羟肟酸、芳基羟胺和 苄醇是导致其 生物转化成化学活性的亲电的 能够共价结合亲核的化合物， 细胞大分子上的位点。 这种共价结合是 导致各种细胞毒性、致突变性和/或 致癌反应。 这项研究的主要目标之一 在本申请中描述的目的是提供对 参与催化活性调节的机制 和催化的芳基磺基转移酶的浓度 含有芳基异羟肟酸的分子的硫酸化， 芳基羟胺和苄醇官能团。 的 本研究的另一个目标是开发定量方法， 评估这些官能的硫酸酯的反应性 组 我们的长期目标是能够准确地 预测硫酸化，以及硫酸酯的后续反应性， 对于新的和现有的药物以及其他异生物质， 含有芳基异羟肟酸、芳基羟胺和苄基 醇官能团。 拟议的研究将利用纯化的酶，分离， 肝细胞以及实现这些目标的免疫化学技术 目标. 芳基磺基转移酶（AST）IV活性的调节将 用纯化的酶和离体大鼠进行研究 肝细胞 AST II和AST IV的相对参与 由分离的大鼠肝细胞催化的硫酸化反应也将 追究 纯化的AST IV将用于开发 测定反应速率常数的定量方法 亲电硫酸酯与模型亲核试剂的反应。 动力学 将确定AST IV催化硫酸化的常数 N-羟基-2-乙酰氨基芴和N-羟基-2- 氨基芴，以及用于所得硫酸盐的反应 与模型亲核试剂的酯。 结构-活性研究将 进行AST IV催化的初级硫酸化， 仲芳基羟胺和芳族二氢二醇。 AST的免疫化学研究将产生关于 肝脏中AST II和AST IV的定位和浓度， 皮肤和呼吸道组织， 异生物质处理的大鼠。 此外，AST IV的分布 在肝脏中，将在慢性 用2-乙酰氨基芴治疗大鼠。

Sulfation of arylhydroxamic acids, arylhydroxylamines, and benzylic alcohols is an essential step leading to their biotransformation into chemically reactive, electrophilic compounds which are capable of binding covalently to nucleophilic sites on cellular macromolecules. This covalent binding is the initial step leading to various cytotoxic, mutagenic, and/or carcinogenic responses. One of the major goals of the research described in this application is to provide an understanding of the mechanisms involved in the regulation of the catalytic activities and concentrations of the aryl sulfotransferse(s) that catalyze sulfation of molecules containing arylhydroxamic acid, arylhydroxylamine, and benzylic alcohol functional groups. The other goal of this research is to develop quantitative methods for assessing the reactivity of the sulfate esters of these functional groups. Our long-term objective is to be able to accurately predict sulfation, and subsequent reactivity of the sulfate ester, for both new and existing drugs as well as other xenobiotics that contain arylhydroxamic acid, arylhydroxylamine, and benzylic alcohol functional groups. The proposed research will utilize purified enzymes, isolated hepatocytes, and immunochemical techniques to accomplish these goals. Regulation of aryl sulfotransferase (AST) IV activity will be studied with the purified enzyme and with isolated rat hepatocytes. The relative participation of AST II and AST IV in sulfation reactions catalyzed by isolated rat hepatocytes will also be investigated. Purified AST IV will be used to develop a quantitative method for determining rate constants for reaction of electrophilic sulfate esters with model nucleophiles. Kinetic constants will be determined for the AST IV-catalyzed sulfation of N-hydroxy-2-acetylaminofluorene and N-hydroxy-2- aminofluorene, as well as for the reaction of the resulting sulfate esters with model nucleophiles. Structure-activity studies will be carried out for the AST IV-catalyzed sulfation of primary and secondary arylhydroxylamines and aromatic dihydrodiols. Immunochemical studies on AST will yield information on the localizations and concentrations of AST II and AST IV in hepatic, cutaneous, and respiratory tract tissues of untreated and xenobiotic-treated rats. Furthermore, the distribution of AST IV in liver will be studied immunohistochemically after chronic treatment of rats with 2-acetylaminofluorene.