title: Characterization of nucleoside triphosphate diphosphohydrolase activity in Trichomonas gallinae and the influence of penicillin and streptomycin in extracellular nucleotide hydrolysis.
abstract: Here we described an nucleoside triphosphate diphosphohydrolase (NTPDase) activity in living trophozoites of Trichomonas gallinae. The enzyme hydrolyzes a variety of purine and pyrimidine nucleoside di- and triphosphates in an optimum pH range of 6.0-8.0. This enzyme activity was activated by high concentrations of divalent cations, such as calcium and magnesium. Contaminant activities were ruled out because the enzyme was not inhibited by classical inhibitors of ATPases (ouabain, 5.0 mM sodium azide, oligomycin) and alkaline phosphatases (levamisole). A significant inhibition of ATP hydrolysis (38%) was observed in the presence of 20 mM sodium azide. Sodium orthovanadate inhibited ATP and ADP hydrolysis (24% and 78%), respectively. The apparent K(M) (Michaelis constant) values were 667.62+/-13 microM for ATP and 125+/-5.3 microM for ADP. V(max) (maximum velocity) values were 0.44+/-0.007 nmol Pi min(-1) per 10(6) trichomonads and 0.91+/-0.12 nmol Pi min(-1) per 10(6) trichomonads for ATP and ADP, respectively. Moreover, we showed a marked decrease in ATP, ADP and AMP hydrolysis when the parasites were grown in the presence of penicillin and streptomycin. The existence of an NTPDase activity in T. gallinae may be involved in pathogenicity, protecting the parasite from the cytolytic effects of the extracellular nucleotides.
authors.affiliation: Instituto de Geriatria e Gerontologia, Pontifícia Universidade Católica do Rio Grande do Sul, Avenida Ipiranga 6681, Porto Alegre, RS, Brazil.
authors.forename: Fernanda Pires
authors.initials: FP
authors.lastname: Borges
authors.forename: Patrícia
authors.initials: P
authors.lastname: de Brum Vieira
authors.forename: Renata C M
authors.initials: RC
authors.lastname: Wiltuschnig
authors.forename: Tiana
authors.initials: T
authors.lastname: Tasca
authors.forename: Geraldo Attilio
authors.initials: GA
authors.lastname: De Carli
authors.forename: Carla Denise
authors.initials: CD
authors.lastname: Bonan
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology; D020536:Enzyme Activators / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D010406:Penicillins / Q000494:pharmacology*; D011684:Purine Nucleosides / Q000378:metabolism; D011741:Pyrimidine Nucleosides / Q000378:metabolism; D011755:Pyrophosphatases / Q000378:metabolism*; D019810:Sodium Azide / Q000494:pharmacology; D013307:Streptomycin / Q000494:pharmacology*; D013379:Substrate Specificity; D014244:Trichomonas / Q000187:drug effects* / Q000201:enzymology*; D053058:Trophozoites / Q000187:drug effects / Q000201:enzymology
chemical_list: D020536:Enzyme Activators; D004791:Enzyme Inhibitors; D010406:Penicillins; D011684:Purine Nucleosides; D011741:Pyrimidine Nucleosides; D019810:Sodium Azide; D011755:Pyrophosphatases; D008274:Magnesium; D002118:Calcium; D013307:Streptomycin