Nare B, Smith J M, Prichard R K
Institute of Parasitology, McGill University, Ste-Anne de Bellevue, Québec, Canada.
Int J Parasitol. 1991 Dec;21(8):919-25. doi: 10.1016/0020-7519(91)90167-6.
The activity of glutathione S-transferase (GST) decreased progressively in Schistosoma mansoni from mice treated with oltipraz (OPZ). However, the peroxidase activity of GST (selenium-independent) and selenium-dependent glutathione peroxidase was not affected by OPZ treatment. Purification and quantification of GST from worms after OPZ treatment indicated that the decrease in enzyme activity was greater than could be accounted for by the decrease in GST protein content. SDS-polyacrylamide gel electrophoresis followed by Western blot analysis with GST isoenzyme specific antisera revealed a slight decrease in the quantity of both 26 and 28 kDa GSTs. Fractionation of cytosolic GSTs from male S. mansoni by chromatofocusing resolved three major isoenzymes (SmI, II and III) and a minor form which eluted first from the column. SmI, II and III all had a molecular weight of about 28 kDa on SDS-polyacrylamide gel electrophoresis. However, on electrophoresis in the absence of SDS, the three GST forms exhibited different mobilities. The pattern of SmI, II and III was similar in untreated and OPZ-treated worms, but the activities of the isoenzymes from treated worms were lower. The results suggest that OPZ interacts with the GST isoenzymes SmI, II and III in a similar manner; thus, the effects are not isoenzyme specific. Taken together, these results suggest that OPZ and/or its metabolites interact directly with GST resulting in inhibition of activity and reduction in total enzyme protein. This mechanism may be important in the antischistosomal action of OPZ.
用奥替普拉（OPZ）处理的小鼠体内曼氏血吸虫中谷胱甘肽S-转移酶（GST）的活性逐渐降低。然而，GST的过氧化物酶活性（不依赖硒）和依赖硒的谷胱甘肽过氧化物酶不受OPZ处理的影响。对OPZ处理后虫体中的GST进行纯化和定量分析表明，酶活性的降低幅度大于GST蛋白含量降低所能解释的范围。SDS-聚丙烯酰胺凝胶电泳后，用GST同工酶特异性抗血清进行Western印迹分析，结果显示26 kDa和28 kDa的GSTs数量均略有减少。通过聚焦层析对雄性曼氏血吸虫的胞质GSTs进行分级分离，解析出三种主要的同工酶（SmI、II和III）以及一种最先从柱上洗脱的次要形式。在SDS-聚丙烯酰胺凝胶电泳上，SmI、II和III的分子量均约为28 kDa。然而，在无SDS的电泳中，这三种GST形式表现出不同的迁移率。未处理和OPZ处理的虫体中SmI、II和III的模式相似，但处理后虫体中同工酶的活性较低。结果表明，OPZ以类似的方式与GST同工酶SmI、II和III相互作用；因此，其作用并非同工酶特异性的。综上所述，这些结果表明OPZ和/或其代谢产物直接与GST相互作用，导致活性抑制和总酶蛋白减少。这种机制可能在OPZ的抗血吸虫作用中起重要作用。
