title: Characterization of an ecto-phosphatase activity in the human parasite Trichomonas vaginalis.
abstract: We have characterized phosphatase activity present on the external surface of Trichomonas vaginalis, using intact living parasites. This enzyme hydrolyzes the substrate p-nitrophenylphosphate (p-NPP) at a rate of 134.3+/-14.8 nmol Pi/h per 10(7) cells. This phosphatase activity decreased by increasing the pH from 6.8 to 8.4, a pH range in which cell viability was maintained for at least 1 h. Experiments using classical inhibitors of acid phosphatases, such as ammonium molybdate and sodium fluoride, as well as inhibitors of phosphotyrosine phosphatase, such as sodium orthovanadate, [monoperoxo(picolinato)oxovanadate(V)] (mpV-PIC) and [potassiumbisperoxo(1,10-phenanthroline)oxovanadate(V)] (bpV-PHEN), showed a decrease in this phosphatase activity, with different patterns of inhibition. Cytochemical analysis showed the localization of this enzyme on the parasite surface (cell body and flagellum) and in intracellular vacuoles. Phosphatase reaction products were also observed in exocytosed membrane-bound material.
authors.affiliation: Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, Cidade Universitária, Ilha do Fundão, 21941-590, Rio de Janeiro, RJ, Brazil.
authors.forename: J B
authors.initials: JB
authors.lastname: de Jesus
authors.forename: T M
authors.initials: TM
authors.lastname: Podlyska
authors.forename: A
authors.initials: A
authors.lastname: Hampshire
authors.forename: C S
authors.initials: CS
authors.lastname: Lopes
authors.forename: M A
authors.initials: MA
authors.lastname: Vannier-Santos
authors.forename: J R
authors.initials: JR
authors.lastname: Meyer-Fernandes
mesh_terms: D009597:4-Nitrophenylphosphatase / Q000378:metabolism; D000135:Acid Phosphatase / Q000378:metabolism*; D000818:Animals; D002462:Cell Membrane / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005407:Flagella / Q000201:enzymology; D006801:Humans; D013379:Substrate Specificity; D014246:Trichomonas vaginalis / Q000201:enzymology* / Q000254:growth & development; D014617:Vacuoles / Q000201:enzymology
chemical_list: D004791:Enzyme Inhibitors; D000135:Acid Phosphatase; D009597:4-Nitrophenylphosphatase