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The penetration protease of the cercariae of Schistosoma mansoni
This thesis is concerned with a study of the proteases released by the cercariae of Schistosoma mansoni while penetrating mammalian skin. The proteases present in secretions collected from the preacetabular glands of cercariae were shown to be active against ¹²⁵I-labelled fibrin but not against unde...
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| Format: | Thesis |
| Language: | English |
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Division of Clinical Immunology
2018
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| _version_ | 1867613342387929088 |
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| access_status_str | Open Access |
| author | Heussen, Christa |
| author2 | Dowdle, Eugene B |
| author_browse | Dowdle, Eugene B Heussen, Christa |
| author_facet | Dowdle, Eugene B Heussen, Christa |
| author_sort | Heussen, Christa |
| collection | Thesis |
| description | This thesis is concerned with a study of the proteases released by the cercariae of Schistosoma mansoni while penetrating mammalian skin. The proteases present in secretions collected from the preacetabular glands of cercariae were shown to be active against ¹²⁵I-labelled fibrin but not against undenatured ³H-collagen. A sensitive solid phase radioenzyme assay, with ¹²⁵I-fibrin as the substrate, was used to show that the cercarial protease could be totally inhibited by serine protease inhibitors such as diisopropylfluorophosphate or phenylmethylsulfonyl fluoride, but not by the sulfhydryl reagents iodoacetamide or p-chloromercuribenzoate. Typical trypsin inhibitors such as soy bean trypsin inhibitor, trasylol or benzamidine inhibited the enzyme to a lesser degree. The active-site labels, TLCK, TPCK and AcAAAACK of trypsin, chymotrypsin and elastase respectively had no effect. Calcium and magnesium stimulated protease activity at concentrations below 0,5 mM, but inhibited at higher concentrations, whereas EDTA had no effect. The pH optimum of the protease lay between pH 9,0 and 9,5. From these studies, I have concluded that the major cercarial penetration protease is an alkaline serine protease with trypsin-like specificity, but not acting via the same mechanism. A technique was developed for examining cercarial proteases in polyacrylamide gels containing SDS and copolymerized gelatin substrate. Bands of proteolytic activity could be detected by negative staining. This method was used to show that cercarial secretions contained one major protease with a molecular weight of 35 000 and that crude enzyme preparations are readily contaminated with bacterial proteases. Partial purification of the major cercarial protease was achieved by cation exchange chromatography. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/27506 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:34:36.552Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2018 |
| publishDateRange | 2018 |
| publishDateSort | 2018 |
| publisher | Division of Clinical Immunology |
| publisherStr | Division of Clinical Immunology |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/27506 The penetration protease of the cercariae of Schistosoma mansoni Heussen, Christa Dowdle, Eugene B Immunology This thesis is concerned with a study of the proteases released by the cercariae of Schistosoma mansoni while penetrating mammalian skin. The proteases present in secretions collected from the preacetabular glands of cercariae were shown to be active against ¹²⁵I-labelled fibrin but not against undenatured ³H-collagen. A sensitive solid phase radioenzyme assay, with ¹²⁵I-fibrin as the substrate, was used to show that the cercarial protease could be totally inhibited by serine protease inhibitors such as diisopropylfluorophosphate or phenylmethylsulfonyl fluoride, but not by the sulfhydryl reagents iodoacetamide or p-chloromercuribenzoate. Typical trypsin inhibitors such as soy bean trypsin inhibitor, trasylol or benzamidine inhibited the enzyme to a lesser degree. The active-site labels, TLCK, TPCK and AcAAAACK of trypsin, chymotrypsin and elastase respectively had no effect. Calcium and magnesium stimulated protease activity at concentrations below 0,5 mM, but inhibited at higher concentrations, whereas EDTA had no effect. The pH optimum of the protease lay between pH 9,0 and 9,5. From these studies, I have concluded that the major cercarial penetration protease is an alkaline serine protease with trypsin-like specificity, but not acting via the same mechanism. A technique was developed for examining cercarial proteases in polyacrylamide gels containing SDS and copolymerized gelatin substrate. Bands of proteolytic activity could be detected by negative staining. This method was used to show that cercarial secretions contained one major protease with a molecular weight of 35 000 and that crude enzyme preparations are readily contaminated with bacterial proteases. Partial purification of the major cercarial protease was achieved by cation exchange chromatography. 2018-02-12T08:43:45Z 2018-02-12T08:43:45Z 1980 Master Thesis Masters MSc http://hdl.handle.net/11427/27506 eng application/pdf Division of Clinical Immunology Faculty of Health Sciences University of Cape Town |
| spellingShingle | Immunology Heussen, Christa The penetration protease of the cercariae of Schistosoma mansoni |
| thesis_degree_str | Master's |
| title | The penetration protease of the cercariae of Schistosoma mansoni |
| title_full | The penetration protease of the cercariae of Schistosoma mansoni |
| title_fullStr | The penetration protease of the cercariae of Schistosoma mansoni |
| title_full_unstemmed | The penetration protease of the cercariae of Schistosoma mansoni |
| title_short | The penetration protease of the cercariae of Schistosoma mansoni |
| title_sort | penetration protease of the cercariae of schistosoma mansoni |
| topic | Immunology |
| url | http://hdl.handle.net/11427/27506 |
| work_keys_str_mv | AT heussenchrista thepenetrationproteaseofthecercariaeofschistosomamansoni AT heussenchrista penetrationproteaseofthecercariaeofschistosomamansoni |