title: Purification and characterization of proteases secreted by transforming schistosomula of Schistosoma mansoni.
abstract: Schistosomula of Schistosoma mansoni which are mechanically transformed at 4 degrees C and are then incubated at 37 degrees C in defined medium spontaneously secrete two proteases, a major one of 28 kDa and a minor one of 60 kDa. These were purified by ion exchange chromatography on DEAE-cellulose and gel filtration on Ultrogel AcA 54 with yields of 33% and 29%, respectively. Both appeared as single bands by silver staining following sodium dodecyl sulphate-polyacrylamide gel electrophoresis analysis. The 28 kDa protease is a glycoprotein that has a pI of 11 or higher and an optimal activity around pH 9.0. It cleaves casein, gelatin and human C3 and C3b. It is metal-ion independent and is inhibited by diisopropyl fluorophosphate, phenylmethanesulfonyl fluoride, soy-bean trypsin inhibitor, alpha 1 antitrypsin, Zn2+ ions, sodium dodecyl sulphate and normal human serum. The 60 kDa protease is a glycoprotein with a pI of 9.2. It can also cleave casein and gelatin and its activity is inhibited by phenylmethanesulfonyl fluoride but not by diisopropyl fluorophosphate or sodium dodecyl sulphate. We suggest that these proteases may play a role during cercarial penetration of the skin and in shedding of the cercarial glycocalyx.
mesh_terms: D000818:Animals; D002364:Caseins / Q000378:metabolism; D003176:Complement C3 / Q000378:metabolism; D003179:Complement C3b / Q000378:metabolism; D003208:Concanavalin A / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005353:Fibronectins / Q000378:metabolism; D006023:Glycoproteins / Q000302:isolation & purification / Q000378:metabolism; D010447:Peptide Hydrolases / Q000302:isolation & purification* / Q000378:metabolism; D011480:Protease Inhibitors / Q000494:pharmacology; D011485:Protein Binding; D012550:Schistosoma mansoni / Q000201:enzymology* / Q000254:growth & development; D019699:Thrombospondins; D014909:Wheat Germ Agglutinins / Q000378:metabolism
chemical_list: D002364:Caseins; D003176:Complement C3; D005353:Fibronectins; D006023:Glycoproteins; D011480:Protease Inhibitors; D019699:Thrombospondins; D014909:Wheat Germ Agglutinins; D003208:Concanavalin A; D003179:Complement C3b; D010447:Peptide Hydrolases