Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/77035
Type: Artigo de periódico
Title: Trypanosoma brucei brucei: Biochemical characterization of ecto-nucleoside triphosphate diphosphohydrolase activities
Author: Leite, MDS
Thomaz, R
Fonseca, FV
Panizzutti, R
Vercesi, AE
Meyer-Fernandes, JR
Abstract: in this work we describe the ability of living cells of Trypanosoma brucei brucei to hydrolyze extracellular ATP. In these intact parasites there was a low level of ATP hydrolysis in the absence of any divalent metal (4.72 +/- 0.51 nmol Pi x 10(-7) cells x h(-1)). The ATP hydrolysis was stimulated by MgCl2 and the Mg-dependent ecto-ATPase activity was 27.15 +/- 2.91 nmol Pi x 10(-7) cells x h(-1). This stimulatory activity was also observed when MgCl2 was replaced by MnCl2. CaCl2 and ZnCl2 were also able to stimulate the ATPase activity, although less than MgCl2. The apparent K-m for ATP was 0.61 mM. This ecto-ATPase activity was insensitive to inhibitors of other ATPase and phosphatase activities. To confirm that this Mg-dependent ATPase activity is an ecto-ATPase activity, we used an impermeable inhibitor, DIDS (4, 4'-diisothiocyanostylbene 2'-2'-disulfonic acid), as well as suramin, an antagonist of P-2 purinoreceptors and inhibitor of some ecto-ATPases. These two reagents inhibited the Mg2+-dependent ATPase activity in a dose-dependent manner. Living cells sequentially hydrolyzed the ATP molecule generating ADP, AMP and adenosine, and supplementation of the culture medium with ATP was able to sustain the proliferation of T brucei brucei as well as adenosine supplementation. Furthermore, the E-NTPDase activity of T brucei brucei is modulated by the availability of purines in the medium. These results indicate that this surface enzyme may play a role in the salvage of purines from the extracellular medium in T brucei brucei. (c) 2006 Elsevier Inc. All rights reserved.
Subject: Trypanosoma brucei brucei
Ecto-ATPase
adenosine
Country: EUA
Editor: Academic Press Inc Elsevier Science
Rights: fechado
Identifier DOI: 10.1016/j.exppara.2006.09.002
Date Issue: 2007
Appears in Collections:Artigos e Materiais de Revistas Científicas - Unicamp

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