Purification and characterization of a 33 kDa serine protease from Acanthamoeba lugdunensis KA/E2 isolated from a Korean keratitis patient

Korean J Parasitol. 2003 Dec;41(4):189-96. doi: 10.3347/kjp.2003.41.4.189.


In order to evaluate the possible roles of secretory proteases in the pathogenesis of amoebic keratitis, we purified and characterized a serine protease secreted by Acanthamoeba lugdunensis KA/E2, isolated from a Korean keratitis patient. The ammonium sulfate-precipitated culture supernatant of the isolate was purified by sequential chromatography on CM-Sepharose, Sephacryl S-200, and mono Q-anion exchange column. The purified 33 kDa protease had a pH optimum of 8.5 and a temperature optimum of 55 degrees C. Phenylmethylsulfonylfluoride and 4-(2- Aminoethyl)-benzenesulfonyl-fluoride, both serine protease specific inhibitors, inhibited almost completely the activity of the 33 kDa protease whereas other classes of inhibitors did not affect its activity. The 33 kDa enzyme degraded various extracellular matrix proteins and serum proteins. Our results strongly suggest that the 33 kDa serine protease secreted from this keratopathogenic Acanthamoeba play important roles in the pathogenesis of amoebic keratitis, such as in corneal tissue invasion, immune evasion and nutrient uptake.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acanthamoeba / enzymology*
  • Acanthamoeba / isolation & purification
  • Acanthamoeba / pathogenicity
  • Acanthamoeba Keratitis / parasitology*
  • Animals
  • Cornea / parasitology
  • Humans
  • Hydrogen-Ion Concentration
  • Korea
  • Serine Endopeptidases / chemistry
  • Serine Endopeptidases / isolation & purification*
  • Serine Endopeptidases / metabolism*
  • Substrate Specificity
  • Temperature
  • Virulence Factors


  • Virulence Factors
  • Serine Endopeptidases