Korean J Parasitol.  2006 Sep;44(3):187-196. 10.3347/kjp.2006.44.3.187.

Molecular and biochemical characterization of hemoglobinase, a cysteine proteinase, in Paragonimus westermani

  • 1Department of Parasitology, Kyungpook National University School of Medicine, Daegu 700-422, Korea. hhkong@knu.ac.kr
  • 2Department of Parasitology, Pusan National University School of Medicine, Busan 602-739, Korea.
  • 3Department of Parasitology, College of Medicine, Seonam University, Namwon, 590-711, Korea.


The mammalian trematode Paragonimus westermani is a typical digenetic parasite, which can cause paragonimiasis in humans. Host tissues and blood cells are important sources of nutrients for development, growth and reproduction of P. westermani. In this study, a cDNA clone encoding a 47 kDa hemoglobinase of P. westermani was characterized by sequencing analysis, and its localization was investigated immunohistochemically. The phylogenetic tree prepared based on the hemoglobinase gene showed high homology with hemoglobinases of Fasciola hepatica and Schistosoma spp. Moreover, recombinant P. westermani hemoglobinase degradaded human hemoglobin at acidic pH (from 3.0 to 5.5) and its activity was almost completely inhibited by E-64, a cysteine proteinase inhibitor. Immunohistochemical studies showed that P. westermani hemoglobinase was localized in the epithelium of the adult worm intestine implying that the protein has a specific function. These observations suggest that hemoglobinase may act as a digestive enzyme for acquisition of nutrients from host hemoglobin. Further investigations may provide insights into hemoglobin catabolism in P. westermani.


Paragonimus westermani; lung fluke; cysteine proteinase; hemoglobinase
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