title: Entamoeba histolytica HM1:IMSS: hemoglobin-degrading neutral cysteine proteases.
abstract: Entamoeba histolytica HMI:IMSS trophozoites were able to utilize human hemoglobin but not hemin as a sole iron source to grow in vitro. Proteases from crude extracts of E. histolytica degraded human, porcine, and bovine hemoglobins at pH 7.0. These proteolytic activities were found by electrophoresis in SDS-polyacrylamide gels copolymerized with hemoglobin, with apparent molecular weights of 116, 82, and 21 kDa, the 82-kDa protein being the most active protease against this substrate. The proteases were classified in the cysteine group since the activities were inhibited by l-trans-epoxysuccinylleucylamido(4-guanidino)butane, p-hydroxymercuribenzoate, iodoacetate, and N-ethylmaleimide and activated with dithiothreitol. Other pathogenic strains of E. histolytica showed the same pattern of hemoglobinases. These hemoglobin-degrading proteases could be playing an important role in iron acquisition by E. histolytica.
authors.affiliation: Departamento de Biología Celular, Centro de Investigación y de Estudios Avanzados del I.P.N., México, D.F., México.
authors.forename: J J
authors.initials: JJ
authors.lastname: Serrano-Luna
authors.forename: E
authors.initials: E
authors.lastname: Negrete
authors.forename: M
authors.initials: M
authors.lastname: Reyes
authors.forename: M
authors.initials: M
authors.lastname: de la Garza
mesh_terms: D000818:Animals; D002417:Cattle; D006224:Cricetinae; D003546:Cysteine Endopeptidases / Q000737:chemistry / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004748:Entamoeba histolytica / Q000201:enzymology* / Q000254:growth & development; D005290:Ferric Compounds / Q000378:metabolism; D015801:Helminth Proteins; D006427:Hemin / Q000378:metabolism; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D013552:Swine
chemical_list: D015853:Cysteine Proteinase Inhibitors; D005290:Ferric Compounds; D015801:Helminth Proteins; D006454:Hemoglobins; D000644:Quaternary Ammonium Compounds; D006427:Hemin; D003546:Cysteine Endopeptidases; C013531:ferric ammonium citrate