Degradations of human immunoglobulins and hemoglobin by a 60 kDa cysteine proteinase of Trichomonas vaginalis |
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Authors: | Duk-Young Min Keun-Hee Hyun Jae-Sook Ryu Myoung-Hee Ahn and Myung-Hwan Cho |
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Institution: | 1Department of Parasitology and Institute of Biomedical Science, Hanyang University College of Medicine, Seoul 133-791, Korea.;2Department of Biology, College of Sciences, Konkuk University, Seoul 143-701, Korea. |
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Abstract: | The present study was undertaken to investigate the role of cysteine proteinase of Trichomonas vaginalis in escaping from host defense mechanism. A cysteine proteinase of T. vaginalis was purified by affinity chromatography and gel filtration. Optimum pH for the purified proteinase activity was 6.0. The proteinase was inhibited by cysteine and serine proteinase inhibitors such as E-64, NEM, IAA, leupeptin, TPCK and TLCK, and also by Hg2+, but not affected by serine-, metallo-, and aspartic proteinase inhibitors such as PMSF, EDTA and pepstatin A. However, it was activated by the cysteine proteinase activator, DTT. The molecular weight of a purified proteinase was 62 kDa on gel filtration and 60 kDa on SDS-PAGE. Interestingly, the purified proteinase was able to degrade serum IgA, secretory IgA, and serum IgG in time- and dose-dependent manners. In addition, the enzyme also degraded hemoglobin in a dose-dependent manner. These results suggest that the acidic cysteine proteinase of T. vaginalis may play a dual role for parasite survival in conferring escape from host humoral defense by degradation of immunoglobulins, and in supplying nutrients to parasites by degradation of hemoglobin. |
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Keywords: | Trichomonas vaginalis cysteine proteinase degradation immunoglobulins hemoglobin |
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