Characterization of an ecto-5'-nucleotidase (EC 3.1.3.5) activity in intact cells of Trichomonas vaginalis.

The enzymatic properties of an ecto-5'-nucleotidase were described in Trichomonas vaginalis. The enzyme hydrolyzes nucleoside monophosphates in optimum pH values of 7.5 and 6.5 for the 30236 strain and for the 30238 strain, respectively. Mg(2+) and Ca(2+) were activators of AMP hydrolysis in both strains. The apparent K(m) (Michaelis constant) values for Mg(2+)-AMP were 111.4+/-28.1 microM (mean+/-SD, n=3) for 30236 strain and 420.2+/-35.7 microM (mean+/-SD, n=3) for 30238 strain. The ecto-5'-nucleotidase activity was insensitive to levamisole and tetramisole, inhibitors of alkaline phosphatases, whereas alpha,beta-methylene-ADP inhibited the enzymatic activity of both strains. Our results showed that the AMP hydrolysis presents differences in some kinetic parameters between the two strains investigated. An analysis of the enzymatic chain involved in the ATP hydrolysis to adenosine will contribute to understanding the biochemical aspects of the parasite and the mechanisms related to host-parasite interactions.