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Type: Artigo de periódico
Title: Phosphatase activity characterization on the surface of intact bloodstream forms of Trypanosoma brucei
Author: Fernandes, EC
Granjeiro, JM
Taga, EM
Meyer-Fernandes, JR
Aoyama, H
Abstract: Procyclic forms of Trypanosoma brucei possess a phosphatase activity on their external cell surface. This activity, while it dephosphorylates [P-32]phosphocasein, is inhibited weakly by NaF and tartrate but strongly by vanadate. In this work, we describe the presence of an external phosphatase activity in intact bloodstream forms of T brucei. With p-nitrophenyl phosphate (pNPP) as substrate, these intact cells produced 3-5 nmol pNP min(-1) mg(-1), linearly for up to at least 30 min. The activity was not significantly increased by Mg2+, Mn2+, Ca2+ and Co2+, but was inhibited by vanadate, NaF, p-chloromercuribenzoate and Zn2+ and was insensitive to okadaic acid. Membrane-enriched fractions of parasites contained an acid phosphatase activity, with a pH optimum in the range of 4.5-5.5. This activity hydrolyzed phosphotyrosine (40 nmol phosphate min(-1) mg(-1)) better than phosphothreonine or phosphoserine. Partial purification of this phosphatase yielded a single activity band following gel electrophoresis, a K-m value of 0.29 mM with pNPP and was insensitive to the Fe2+/H2O2/ascorbate system. (C) 2003 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.
Subject: phosphotyrosine phosphatase
bloodstream forms
Trypanosoma brucei
Country: EUA
Editor: Wiley-blackwell
Rights: fechado
Identifier DOI: 10.1016/S0378-1097(03)00091-0
Date Issue: 2003
Appears in Collections:Unicamp - Artigos e Outros Documentos

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