Article
Characterization of an ecto-5'-nucleotidase activity present on the cell surface of Tritrichomonas foetus
Registro en:
JESUS, José Batista de; GOMES, Daniela Cosentino; FERNANDES, José Roberto Meyer. Characterization of an ecto-5 -nucleotidase activity present on the cell surface of Tritrichomonas foetus. Veterinary Parasitology, v.179, p.50-56, 2011.
0304-4017
10.1016/j.vetpar.2011.01.061
1873-2550
Autor
Jesus, José Batista de
Gomes, Daniela Cosentino
Fernandes, José Roberto Meyer
Resumen
Tritrichomonas foetus is the causative agent of sexually transmitted trichomoniasis in cattle. In females, the infection can be associated with infertility, vaginitis, endometritis, abortion or pyometra, leading to significant economic losses in cattle raising. T. foetus is devoid of the ability to synthesize purine nucleotides de novo, depending instead on salvaging purines from the host environment. Ecto-5'-nucleotidase catalyzes the final step of extracellular nucleotide degradation, the hydrolysis of nucleoside 5'-monophosphates to the corresponding nucleosides and Pi. In this work we show that living, intact cells of T. foetus were able to hydrolyze 5'AMP at a rate of 12.57 ± 1.23 nmol Pi × h(-1) × 10(-7) cells at pH 7.2 and the 5'AMP hydrolysis is due to a plasma membrane-bound ecto-enzyme activity. The apparent K(m) for 5'AMP was 0.49 ± 0.06 mM. In addition to 5'AMP, the enzyme hydrolyzed all substrate monophosphates tested except 3'AMP. No divalent metals or metal chelators were able to modulate enzyme activity. Phosphatase inhibitors did not have an effect on ecto-5'-nucleotidase activity while ammonium molybdate did inhibit the activity in a dose dependent manner. The presence of adenosine in the culture medium negatively modulated the enzyme. These results indicate the existence of an ecto-5'-nucleotidase that may play a role in the salvage of purines.