title: Characterization of an ecto-5'-nucleotidase (EC 3.1.3.5) activity in intact trophozoites of Trichomonas gallinae.
abstract: This study describes the enzymatic properties of an ecto-5'-nucleotidase in Trichomonas gallinae. The enzyme hydrolyzes nucleoside monophosphates at pH 7.2 and is activated by divalent cations, such as magnesium. Ecto-5'-nucleotidase activity was insensitive to levamisole, tetramisole (alkaline phosphatase inhibitors), and AMPCP (adenosine 5'-[alpha,beta-methylene]diphosphate), an ecto-5'-nucleotidase inhibitor, whereas 0.1mM ammonium molybdate (considered a potent inhibitor of 5'-nucleotidase activity) completely inhibited the enzyme activity. The apparent K(M) (Michaelis constant) and Vmax (maximum velocity) values for Mg2+-AMP were 466+/-57 microM and 3.7+/-0.59 nmolPi/min/10(6) trichomonads, respectively. Considering that trichomonads lack the ability to synthesize purines and pyrimidines de novo, the presence of an ecto-5'-nucleotidase in intact trophozoites of T. gallinae could be important in regulating the extracellular nucleotide levels and generating adenosine, essential for the survival strategies of the parasite.
authors.affiliation: Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, RS, Brazil.
authors.forename: Fernanda Pires
authors.initials: FP
authors.lastname: Borges
authors.forename: Bárbara
authors.initials: B
authors.lastname: Gottardi
authors.forename: Cristiane
authors.initials: C
authors.lastname: Stuepp
authors.forename: Anne Brandolt
authors.initials: AB
authors.lastname: Larré
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: D015720:5'-Nucleotidase / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D000249:Adenosine Monophosphate / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000037:antagonists & inhibitors; D000818:Animals; D000994:Antitrichomonal Agents / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D007978:Levamisole / Q000494:pharmacology; D008274:Magnesium / Q000378:metabolism; D013773:Tetramisole / Q000494:pharmacology; D014244:Trichomonas / Q000201:enzymology*; D014245:Trichomonas Infections / Q000469:parasitology / Q000662:veterinary*
chemical_list: D000994:Antitrichomonal Agents; D004791:Enzyme Inhibitors; D007978:Levamisole; D000249:Adenosine Monophosphate; D013773:Tetramisole; D000469:Alkaline Phosphatase; D015720:5'-Nucleotidase; D008274:Magnesium; D002118:Calcium