Characterization of an ecto-5'-nucleotidase (EC 3.1.3.5) activity in intact trophozoites of Trichomonas gallinae.
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.
Borges
Fernanda Pires
FP
Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, RS, Brazil.
Gottardi
Bárbara
B
Stuepp
Cristiane
C
Larré
Anne Brandolt
AB
Tasca
Tiana
T
De Carli
Geraldo Attilio
GA
Bonan
Carla Denise
CD
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*
D000994:Antitrichomonal Agents; D004791:Enzyme Inhibitors; D007978:Levamisole; D000249:Adenosine Monophosphate; D013773:Tetramisole; D000469:Alkaline Phosphatase; D015720:5'-Nucleotidase; D008274:Magnesium; D002118:Calcium