Characterization of an ecto-5′-nucleotidase (EC 3.1.3.5) activity in intact trophozoites of Trichomonas gallinae

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• 作者：Fern ; a Pires Borges ; Bá ; rbara Gottardi ; Cristiane Stuepp ; Anne Br ; olt Larré ; Tiana Tasca ; Geraldo Attilio De Carli ; Carla Denise Bonan
• 关键词：Adenosine ; Ecto-5′ ; -nucleotidase ; Extracellular nucleotides ; Trichomonas gallinae
• 刊名：Veterinary Parasitology
• 出版年：2007
• 期刊代码：107_03044017
• 类别：abs
• 出版时间：31 January 2007
• 卷：143
• 期：2
• 页码：106-111
• 文件大小：191 K

摘要

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′-[α,β-methylene]diphosphate), an ecto-5′-nucleotidase inhibitor, whereas 0.1 mM ammonium molybdate (considered a potent inhibitor of 5′-nucleotidase activity) completely inhibited the enzyme activity. The apparent K_M (Michaelis constant) and V_max (maximum velocity) values for Mg²⁺-AMP were 466 ± 57 μM and 3.7 ± 0.59 nmolPi/min/10⁶ 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.