title: A novel ecto-phosphatase activity of Herpetomonas muscarum muscarum inhibited by platelet-activating factor.
abstract: In the present work ecto-phosphatase activity in Herpetomonas muscarum muscarum has been characterized using live parasites. This enzyme hydrolyzed p-nitrophenylphosphate at a rate of 4.27 nmol Pi/mg of protein.min. A pH curve was generated, in which these intact flagellates showed the highest phosphatase activity at pH 6.5. Classical inhibitors for acid phosphatase, such as sodium orthovanadate, sodium tartrate, and ammonium molybdate, were used in the experiments and showed different patterns of inhibition. Lithium fluoride, aluminum chloride, and fluoroaluminate complexes were also tested. Although lithium fluoride and fluoroaluminate complexes were capable of inhibiting the phosphatase activity, aluminum chloride stimulated this enzyme. Cytochemical analysis showed the localization of this enzyme on the parasite surface. This ecto-phosphatase activity was also significantly diminished when the parasites were treated with 10(-6) M platelet-activating factor (PAF), a potent phospholipid mediator that promoted cellular differentiation in this parasite.
authors.affiliation: Departamento de Patologia e Laboratórios, F.C.M., UERJ, Rio de Janeiro, Brazil.
authors.forename: P M
authors.initials: PM
authors.lastname: Dutra
authors.forename: C O
authors.initials: CO
authors.lastname: Rodrigues
authors.forename: J B
authors.initials: JB
authors.lastname: Jesus
authors.forename: A H
authors.initials: AH
authors.lastname: Lopes
authors.forename: T
authors.initials: T
authors.lastname: Souto-Padrón
authors.forename: J R
authors.initials: JR
authors.lastname: Meyer-Fernandes
mesh_terms: D009597:4-Nitrophenylphosphatase / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002474:Cell-Free System; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006868:Hydrolysis; D007700:Kinetics; D010972:Platelet Activating Factor / Q000494:pharmacology*; D014351:Trypanosomatina / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*
chemical_list: D004791:Enzyme Inhibitors; D010972:Platelet Activating Factor; D009597:4-Nitrophenylphosphatase