ARYL SULFOTRANSFERASE IN DRUG AND XENOBIOTIC METABOLISM

芳基异羟肟酸、芳基羟胺和 苄基醇是导致其 生物转化为化学反应活跃的亲电性 能够与亲核试剂共价结合的化合物 细胞大分子上的位置。这种共价结合是 导致各种细胞毒性、诱变性和/或 致癌反应。这项研究的主要目标之一 本应用程序中描述的内容是为了让您了解 参与催化活性调节的机制 和催化的芳基硫转移酶(S)的浓度 含有芳基异羟肟酸的分子的硫酸盐化， 芳基羟胺和苯甲醇官能团。这个 这项研究的另一个目标是开发定量方法 评估这些官能团的硫酸酯的反应性 组。我们的长期目标是能够准确地 预测硫酸盐化，以及随后硫酸酯的反应活性， 对于新的和现有的药物以及其他具有 含有芳基异羟肟酸、芳基羟胺和苯甲酸 酒精官能团。 拟议的研究将利用纯化的酶，分离出 肝细胞，以及免疫化学技术来完成这些 目标。芳基磺基转移酶(AST)IV活性的调节 用纯化的酶和分离的大鼠进行研究 肝细胞。天冬氨酸氨基转移酶II和天冬氨酸氨基转移酶IV的相对参与 由分离的大鼠肝细胞催化的硫化反应也将 被调查。纯化的AST IV将用于开发一种 定量测定反应速率常数的方法 亲电性硫酸酯与模型亲核试剂的结合。动能 将确定AST IV催化的硫酸盐化的常数 N-羟基-2-乙酰氨基荧烯和N-羟基-2-呋喃 氨基荧烯以及生成的硫酸盐的反应 含有模型亲核试剂的酯。结构-活性研究将是 进行了AST IV催化的原生和硫化反应 仲芳基羟胺和芳香族二氢二醇。 对AST的免疫化学研究将提供有关 AST II和AST IV在肝脏中的定位和浓度 未经治疗的皮肤和呼吸道组织 异种生物处理的大鼠。此外，天冬氨酸转氨酶IV的分布 用免疫组织化学方法研究慢性阻塞性肺疾病后肝脏中的 用2-乙酰氨基荧酮处理大鼠。

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.