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Korean J Parasitol > Volume 35(2):1997 > Article

Brief Communication
Korean J Parasitol. 1997 Jun;35(2):139-142. English.
Published online Jun 20, 1997.  http://dx.doi.org/10.3347/kjp.1997.35.2.139
Copyright © 1997 by The Korean Society for Parasitology
Activities of different cysteine proteases of Paragonimus westermani in cleaving human IgG
Y B Chung,1H J Yang,2S Y Kang,3Y Kong,2 and S Y Cho*1
1Department of Parasitology, Catholic University of Korea, School of Medicine, Seoul 137-701, Korea.
Received May 27, 1997; Accepted June 03, 1997.


Cleaving host immunoglobulins is a well known mechanism of evading host immune reactions exploited by helminth parasites. Secreted cysteine proteases of helminth are a part of enzymes cleaving host IgG. Paragonimus westermani produces at least six different species of the cysteine protease in its developmental stages. This study was undertaken to evaluate comparatively the activities against human IgG by the different enzymes. When the metacercariae, which secrete 27 and 28 kDa cysteine proteases, were incubated in human IgG solution, IgG was degraded at its hinge region. Further incubation resulted complete hydrolysis. From 4-week and 7-week old juveniles and 16-week old adults of P. westermani, five different enzymes at 15, 17, 27, 28 and 53 kDa have been purified, if the enzyme with the same molecular mass is regarded to be identical. In cleaving human IgG, each cysteine protease exhibited decreasing activities with age.


Fig. 1
(A) Immunoblot analysis of IgG cleavage. Twenty, newly excysted live metacercariae were incubated in human IgG solution (3 mg/ml) for 1 hour (lane 1), 3 hours (lane 2) and 10 hours (lane3) at 37℃. The reactants were separated by 7.5-15% SDS-PAGE, transferblotted to PVDF membrane and probed with anti-human Fab. A degradation product at 32 kDa (▸) was detected. Ten hour incubation exhibited complete hydrolysis of the reacted IgG. Heavy (★) and light chain (☆) of IgG. Mr, molecular weight in kDa; C, control IgG. (B) Degradation of human IgG by purified cysteine proteases from 4 different stages of P. westermani. The reaction mixtures were incubated for 2 hour at 37℃ and separated in 7.5-15% SDS-PAGE and Coomassie stained. Digestion products at 32 (▸), 15 (→) and 10(→) kDa were detected. Numbers at the top of the figure indicated the Mr of the purified enzymes and numbers in the second row, the age of P. westermani in weeks. C, control IgG; MC, metacercariae. (C) Cleavage of IgG by the 28 kDa cysteine proteases purified from different maturation stages. The reaction mixtures were incubated for 30 minutes at 37℃ and resolved by 7.5-15% SDS-PAGE, then Coomassie stained. Markings are the same as described in (B).

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