The major neutral proteinase of Entamoeba histolytica

J Exp Med. 1986 Mar 1;163(3):536-49. doi: 10.1084/jem.163.3.536.


FPLC anion-exchange and chromatofocusing chromatography were used to purify the major neutral proteinase from secretions of axenically cultured Entamoeba histolytica trophozoites. HM-1 strain trophozoites, which were more proteolytically active than the less virulent HK-9 strain, were used for purification of the enzyme. It is a thiol proteinase with a subunit Mr of approximately 56,000, a neutral pH optimum, and a pI of 6. The importance of this enzyme in extraintestinal amoebiasis is suggested by its ability to degrade a model of connective tissue extracellular matrix as well as purified fibronectin, laminin, and type I collagen. The enzyme caused a loss of adhesion of mammalian cells in culture, probably because of its ability to degrade anchoring proteins. Experiments with a peptide substrate and inhibitors indicated that the proteinase preferentially binds peptides with arginine at P-1. It is also a plasminogen activator, and could thus potentiate host proteinase systems.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Cell Adhesion
  • Chromatography, Ion Exchange
  • Cysteine Endopeptidases
  • Endopeptidases / isolation & purification
  • Endopeptidases / metabolism*
  • Entamoeba histolytica / enzymology*
  • Extracellular Matrix / metabolism
  • Hydrogen-Ion Concentration
  • Neprilysin
  • Protease Inhibitors


  • Protease Inhibitors
  • Endopeptidases
  • Cysteine Endopeptidases
  • Neprilysin