title: The cysteine proteinases of Schistosoma mansoni cercariae.
abstract: Based on substrate preferences, cercariae of Schistosoma mansoni were seen to express both cathepsin L and cathepsin B cysteine proteinases, although the former activity was many-fold greater. Two cathepsin L activities identified in cercarial extracts by zymography co-migrated with activities in extracts of 3 h and 24 h schistosomula and in extracts of adult worms. Since these enzymes have been implicated in haemoglobin digestion by adult worms, they may perform a similar function in schistosomula. Immunolocalization using scanning electron micrographs showed that cathepsin L and cathepsin B proteinases were present in the cercarial post-acetabular glands. In addition, cercarial serine proteinase activities considered to facilitate skin penetration efficiently cleaved the substrates Z-Gly-Pro-Arg-NHMec and Z-Gly-Pro-Lys-NHMec. Cercariae release most of this serine proteinase activity when induced to secrete the contents of their acetabular glands. In contrast, newly transformed 3 h and 24 h schistosomula did not express this activity.
authors.affiliation: Molecular Parasitology Unit, Queensland Institute of Medical Research, Australia.
authors.forename: J P
authors.initials: JP
authors.lastname: Dalton
authors.forename: K A
authors.initials: KA
authors.lastname: Clough
authors.forename: M K
authors.initials: MK
authors.lastname: Jones
authors.forename: P J
authors.initials: PJ
authors.lastname: Brindley
mesh_terms: D000818:Animals; D002401:Cathepsin B / Q000032:analysis / Q000378:metabolism; D056668:Cathepsin L; D002403:Cathepsins / Q000032:analysis / Q000378:metabolism*; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D010450:Endopeptidases; D005260:Female; D007814:Larva / Q000201:enzymology / Q000648:ultrastructure; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008855:Microscopy, Electron, Scanning; D016253:Microscopy, Immunoelectron; D051381:Rats; D017208:Rats, Wistar; D012550:Schistosoma mansoni / Q000201:enzymology* / Q000302:isolation & purification / Q000472:pathogenicity; D012867:Skin / Q000469:parasitology; D013379:Substrate Specificity
chemical_list: D002403:Cathepsins; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; D002401:Cathepsin B; D056668:Cathepsin L; C534278:Ctsl protein, mouse; C534280:Ctsl protein, rat