日本血吸虫血红素降解酶系的研究(英文)

PRESENCE OF HEME DEGRADING ENZYMES IN ADULT WORMS OF SCHISTOSOMA JAPONICUM

目的 研究日本血吸虫成虫中血红素加氧酶和胆绿素还原酶的活性以及酶的生物学特性。 方法 从日本血吸虫成虫的匀浆组织中抽提微粒体蛋白组分并制备匀浆上清 ,分别用特异性底物检测微粒体和匀浆上清中血红素加氧酶 (HO)和胆绿素还原酶 (BR)的活性 ,并研究这两种酶活性的时间依赖性和 pH值依赖性。 结果 在日本血吸虫成虫的微粒体和匀浆上清中分别检测到HO和BR ,其酶的比活性分别为 5 6.7nmolbilirubin/ (mg·min)和 43 .4nmolbilirubin/ (mg·min)。在这两种酶促反应中 ,10min前酶促反应速率呈线形上升 ,15min后进入平台期 ,反应趋于饱和。成虫匀浆抽提物体外降解血红素的反应对 pH值有依赖性 ,HO和BR反应的最佳 pH环境均为pH 8.7。 结论 日本血吸虫成虫具有完整的血红素降解酶系统。

Objective To Investigate enzymes involved in heme degradation by adult worms of schistosome and to biochemically characterise of the enzymes. Methods Homogenate of adult worms of Schistosoma japonicum was prepared, and activities of heme oxygenase and biliverdin reductase were detected by incubation with the respective specific substrates. The pH- and time-dependency of the enzymatic activities was also studied. Results Adult worms of S. japonicum were shown to possess important enzymes of the heme degrading system, heme oxygenase (HO) and biliverdin reductase (BR). The specific activities of HO and BR were 56.7 nmol bilirubin/(mg·min) and 43.4 nmol bilirubin/(mg·min), respectively. Degradation of heme by the extracts of adult worms was pH-dependent. Conclusion The findings of this study demonstrate the presence of enzymes in S. japonicum , which are able to catabolize the heme. It is inferred that heme from host can be further degraded by the parasite.