title: Excystment of Paragonimus westermani metacercariae by endogenous cysteine protease.
abstract: To infect definitive or paratenic hosts, metacercariae of Paragonimus westermani should excyst in the host intestine. Optimum conditions for the excystment have been known to be pH 8-9 and a temperature of 40 C. Under these conditions, excystment of P. westermani metacercariae was accelerated in the presence of 1 mM dithiothreitol (DTT). The DTT acceleration was antagonized dose-dependently by cysteine protease inhibitors of L-trans-epoxysuccinylleucylamido(4-guanidino)butane (E-64, 2-20 microM) or leupeptin (0.1-1 mM), suggesting that certain cysteine proteases of the metacercaria are involved in excystment. Protease activities were detected in excretory-secretory products (ESP) of newly excysted metacercariae. Two distinct proteases were purified by DEAE anion-exchange chromatography of the ESP. While a 27-kDa protease exhibited endodipeptidolytic activity at pH 5-8.5 and remained stable at neutral pH for 3 days, the 28-kDa enzyme was stable at pH 5-7.5, with lower activity at pH 8.5. Both proteases hydrolyzed collagen, fibronectin, and myosin within 1 hr at pH 8. These results suggest that cysteine proteases secreted by P. westermani metacercariae modulate excystment.
authors.affiliation: Department of Parasitology, College of Medicine, Chung-Ang University, Seoul, Korea.
authors.forename: Y B
authors.initials: YB
authors.lastname: Chung
authors.forename: Y
authors.initials: Y
authors.lastname: Kong
authors.forename: I J
authors.initials: IJ
authors.lastname: Joo
authors.forename: S Y
authors.initials: SY
authors.lastname: Cho
authors.forename: S Y
authors.initials: SY
authors.lastname: Kang
mesh_terms: D000818:Animals; D002852:Chromatography, Ion Exchange; D003094:Collagen / Q000378:metabolism; D003374:Coumarins / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000302:isolation & purification / Q000502:physiology*; D004151:Dipeptides / Q000378:metabolism; D004229:Dithiothreitol / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D005353:Fibronectins / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007460:Iodoacetamide / Q000494:pharmacology; D007930:Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D007976:Leupeptins / Q000494:pharmacology; D009218:Myosins / Q000378:metabolism; D009842:Oligopeptides / Q000378:metabolism; D010196:Pancreatic Elastase / Q000494:pharmacology; D010238:Paragonimus / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D013696:Temperature; D014357:Trypsin / Q000494:pharmacology
chemical_list: D003374:Coumarins; D004151:Dipeptides; D005353:Fibronectins; D007976:Leupeptins; D009842:Oligopeptides; C070514:N-benzyloxycarbonyl-alanyl-arginyl-arginine 4-methoxy-2-naphthylamide; C021159:benzyloxycarbonyl-phenylalanylarginine-4-methylcoumaryl-7-amide; D003094:Collagen; D010196:Pancreatic Elastase; D014357:Trypsin; D003546:Cysteine Endopeptidases; D009218:Myosins; D007930:Leucine; C032854:leupeptin; C024974:E 64; D004229:Dithiothreitol; D007460:Iodoacetamide