Abstract: 　Objective To explore the activity of heme oxygenase and immunolocate the enzyme in the adult worms of Schistosoma japonicum .Methods Microsomal protein was isolated from the homogenate of adult S.japonicum , heme degradation and effect of different pH conditions and buffers on degrading reaction were investigated by incubating microsomal protein with hemin. The slices of whole worm and cells of S.japonicum were prepared, distribution of HO in schistosome was studied by immunofluorescent and alkaline phosphatase(AP) -immunocytochemical assays.Results Microsomal protein of adult worms can degrade the heme in vitro , the activity being 56.7 nmol bilirubin/(mg·min).The optimal pH was 8.7. Immunofluorescent and AP-immunocytochemical assays revealed that the HO distributed dispersively in the worm, and located in cytoplasm.Conclusion The presence of HO was firstly proved in S.japonicum .

Key words: Schistosoma japonicum, heme oxygenase, pH-dependency, Immunohistochemistry