Entamoeba histolytica: Soluble and membrane-associated neutral sphingomyelinase-C and other unidentified esterase activity |
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| Authors: | Javier Vargas-Villarreal,Carlos Herná ndez-Luna,Victor M. Torres de la Cruz,Francisco Gonzá lez-Salazar,Brenda Leticia Escobedo-Guajardo,Salvador Said-Ferná ndez |
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| Affiliation: | a División de Biología Celular y Molecular, Centro de Investigación Biomédica del Noreste, Instituto Mexicano del Seguro Social, Administración de correo No. 4, Apartado Postal 020-E, Colonia Independencia, Monterrey CP 64720, Nuevo León, Mexico
b Laboratorio de Enzimología de la Facultad de Ciencias Biológicas. Universidad Autónoma de Nuevo León, San Nicolás de los Garza, Nuevo León, Mexico |
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| 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 Mg2+, Mn2+, or Co2+, and inhibited by Zn2+, Hg2+, Ca2+, 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. |
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| Keywords: | Amoebae Entamoeba histolytica Sphingomyelinase-C EC 3.1.4.12 Sphingomyelinase-D EC 3.1.4.41 Phosphorylcholine phosphatase EC 3.1.3.75 Cytolysins Lipid metabolism |
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