title: Entamoeba histolytica: soluble and membrane-associated neutral sphingomyelinase-C and other unidentified esterase activity.
abstract: Sphingomyelinase (SMase) activity was measured in Entamoeba histolytica particulate and soluble subcellular fractions. The effects on SMase of incubation time, total protein concentration, pH, and several divalent cations were determined. SMase-C and other unidentified esterase activity were detected in soluble and particulate fractions. SMase-C was 94.5-96.0% higher than the unidentified esterase activity. Soluble and insoluble SMase-C specific activities increased with protein dose and incubation time. Soluble and insoluble SMase-C activities were maximum at pH 7.5 and were dependent on Mg(2+), Mn(2+), or Co(2+), and inhibited by Zn(2+), Hg(2+), Ca(2+), and EDTA. SMase-C was active in the pH range of 3-10 and its maximum activity was at pH 7.5. The soluble and insoluble SMases have remarkably similar physicochemical properties, strongly suggesting that E. histolytica has just one isoform of neutral SMase-C that had not been described before and might be essential for E. histolytica metabolism or virulence.
authors.affiliation: División de Biología Celular y Molecular, Centro de Investigación Biomédica del Noreste, Instituto Mexicano del Seguro Social, Administración de correo No. 4, Colonia Independencia, Monterrey, Nuevo León, Mexico.
authors.forename: Javier
authors.initials: J
authors.lastname: Vargas-Villarreal
authors.forename: Rebeca
authors.initials: R
authors.lastname: Palacios-Corona
authors.forename: Carlos
authors.initials: C
authors.lastname: Hernández-Luna
authors.forename: Benito David
authors.initials: BD
authors.lastname: Mata-Cárdenas
authors.forename: Victor M
authors.initials: VM
authors.lastname: Torres de la Cruz
authors.forename: Elva I
authors.initials: EI
authors.lastname: Cortés-Gutiérrez
authors.forename: Francisco
authors.initials: F
authors.lastname: González-Salazar
authors.forename: Jesús Norberto
authors.initials: JN
authors.lastname: Garza-González
authors.forename: Brenda Leticia
authors.initials: BL
authors.lastname: Escobedo-Guajardo
authors.forename: Salvador
authors.initials: S
authors.lastname: Said-Fernández
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology; D003035:Cobalt / Q000494:pharmacology; D006224:Cricetinae; D004305:Dose-Response Relationship, Drug; D004748:Entamoeba histolytica / Q000201:enzymology* / Q000472:pathogenicity; D004950:Esterases / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D008345:Manganese / Q000494:pharmacology; D008628:Mercury / Q000494:pharmacology; D008647:Mesocricetus; D015800:Protozoan Proteins / Q000378:metabolism; D013108:Sphingomyelin Phosphodiesterase / Q000187:drug effects / Q000378:metabolism*; D013997:Time Factors; D014774:Virulence; D015032:Zinc / Q000494:pharmacology
chemical_list: D015800:Protozoan Proteins; D003035:Cobalt; D008345:Manganese; D004950:Esterases; D013108:Sphingomyelin Phosphodiesterase; D008628:Mercury; D008274:Magnesium; D015032:Zinc; D002118:Calcium