title: The major neutral proteinase of Entamoeba histolytica.
abstract: 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.
authors.forename: W E
authors.initials: WE
authors.lastname: Keene
authors.forename: M G
authors.initials: MG
authors.lastname: Petitt
authors.forename: S
authors.initials: S
authors.lastname: Allen
authors.forename: J H
authors.initials: JH
authors.lastname: McKerrow
mesh_terms: D000818:Animals; D002448:Cell Adhesion; D002852:Chromatography, Ion Exchange; D003546:Cysteine Endopeptidases; D010450:Endopeptidases / Q000302:isolation & purification / Q000378:metabolism*; D004748:Entamoeba histolytica / Q000201:enzymology*; D005109:Extracellular Matrix / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D015260:Neprilysin; D011480:Protease Inhibitors
chemical_list: D011480:Protease Inhibitors; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; D015260:Neprilysin