Objective: To investigate the Entamoeba histolytica living in the low oxygen concentration colon of the host and how does it survive in the circumstance after invading the tissues with high oxygen concentration while obtaining oxygen without being damaged by the toxins.
Material and methods: E. histolytica cultured for 48 hours was collected, centrifuged, rinsed, ultrasonically shattered and again centrifuged, and the activities of superoxide dismutase and the catalase in the supernatant were determined. The catalase and peroxidase were identified by the electron microscopic enzyme cytochemical reaction technique.
Results: E. histolytica contained 122.42 +/- 15.47 U/mgpr of superoxide dismutase, 126.05 +/- 17.04 K/mgpr of catalase and peroxidase, and all of them are detoxifying enzymes. Catalase and peroxidase were located within microsomes and lysosome-like organelles respectively.
Conclusions: E. histolytica contains the detoxifying enzymes as superoxide dismutase, catalase and peroxidase, that may prevent the aerobic metabolism from being poisoned by the activated oxygen free radical (superoxide anion radical and hydrogen peroxide) produced in this process, suggesting that the detoxifying function of these enzymes play an important defensive role in the survival of E. histolytica.