Entamoeba histolytica: soluble and membrane-associated neutral sphingomyelinase-C and other unidentified esterase activity.
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.
Vargas-Villarreal
Javier
J
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.
Palacios-Corona
Rebeca
R
Hernández-Luna
Carlos
C
Mata-Cárdenas
Benito David
BD
Torres de la Cruz
Victor M
VM
Cortés-Gutiérrez
Elva I
EI
González-Salazar
Francisco
F
Garza-González
Jesús Norberto
JN
Escobedo-Guajardo
Brenda Leticia
BL
Said-Fernández
Salvador
S
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
D015800:Protozoan Proteins; D003035:Cobalt; D008345:Manganese; D004950:Esterases; D013108:Sphingomyelin Phosphodiesterase; D008628:Mercury; D008274:Magnesium; D015032:Zinc; D002118:Calcium