ROLE OF GLUTATHIONE IN DRUG METABOLISM BY SCHISTOSOMES

据估计，血吸虫病困扰着2亿多人。 全世界。在实用的疫苗问世之前，化疗将 对于治疗感染者和 控制人口内传播的方案。意义重大 迈向合理发展的新路，更有成效 通过对抗血吸虫药物的详细了解，将有助于开发抗血吸虫药物 药物与寄生虫相互作用的生化机制。是这样的 相互作用不仅包括药物对寄生虫的影响，还包括 还有寄生虫对药物的影响。因此，两国之间的差异 血吸虫对外源化合物的酶解毒能力 可以解释药物中观察到的一些菌株或物种的差异 敏感度。 这一提议旨在检验这样一种假设，即与 还原型谷胱甘肽(GSH)是一种外源代谢途径。 血吸虫，并可能参与一些药物的解毒 寄生虫。研究将集中在血吸虫谷胱甘肽S转移酶 (GST)及其在催化这种共轭反应中的作用。这个 推测的谷胱甘肽偶联物的后续命运也将被考虑。 具体的实验目标如下：1)使用现有的分析方法 对于GST，调查无细胞催化的GSH依赖反应的类型 曼氏血吸虫制剂；2)纯化曼氏血吸虫成虫GST 亲和层析和高压液相色谱； 纯化的酶/同工酶的物理化学特性 标准物质的性质、催化作用和配体结合作用 生化技术；3)用模型底物和特异性抗血清， 曼氏血吸虫发育过程中GST表达的变化 从尾蚴到成虫；4)类似地，探索血吸虫GST是否 用某些外源物质诱导；5)比较S. 确定曼氏杆菌和苏云金杆菌是否存在物种差异 代谢敌敌畏的能力，敌敌畏是甲氰菊酯的活性形式，可以 解释了不同物种对该药物的敏感性；以及6) 用放射性标记的模型药物和高压液相色谱 分析、确定曼氏血吸虫成虫是否分泌GSH硫醚 直接偶联或是否进一步代谢成其他药物 硫代尿酸等产品。

Schistosomiasis is estimated to afflict well over 200 million people worldwide. Until a practical vaccine is available, chemotherapy will continue to be important both for treating infected individuals and in programs for controlling transmission within populations. Significant advances toward the rational development of new, more effective antischistosomal drugs will be facilitated by a detailed understanding of the biochemical mechanisms underlying drug-parasite interactions. Such interactions include not only the effects of a drug on the parasite, but also effects of the parasite on the drug. Thus, differences in the capacity of schistosomes to enzymatically detoxicate xenobiotic compounds could explain some observed strain or species differences in drug susceptibility. This proposal is designed to test the hypothesis that conjugation with reduced glutathione (GSH) is a pathway of xenobiotic metabolism in schistosmes and may be involved in the detoxication of some drugs by these parasites. Studies will focus on schistosomal glutathione S-transferases (GST) and their role in catalyzing such conjugation reactions. The subsequent fate of putative GSH conjugates will also be considered. Specific experimental objectives are as follows: 1) Using existing assays for GST, survey the types of GSH-dependent reactions catalyzed by cell-free Schistosoma mansoni preparations; 2) Purify GST from adult S. mansoni by affinity chromatography and high pressure liquid chromatography; characterize the purified enzyme/isoenzymes with respect to physicochemical properties and catalytic and ligand binding functions using standard biochemical techniques; 3) With model substrates and specific antisera, document changes in the expression of GST in S. mansoni during development from cercaria to adult; 4) Similarly, explore whether schistosomal GST is inducible by treatment with certain xenobiotics; 5) compare GST in S. mansoni and S. hematobium to determine whether species differences in the capacity to metabolize dichlorvos, the active form of metrifonate, can account for the differential species susceptibility to that drug; and 6) With a radiolabeled model drug and high pressure liquid chromatograhic analysis, determine whether adult S. mansoni excrete GSH thioether conjugates directly or whether these are further metabolized to other drug products such as mercapturic acids.