Phosphatase activity characterization on the surface of intact bloodstream forms of Trypanosoma brucei

Procyclic forms of Trypanosoma brucei possess a phosphatase activity on their external cell surface. This activity, while it dephosphorylates [32P]phosphocasein, is inhibited weakly by NaF and tartrate but strongly by vanadate. In this work, we describe the presence of an external phosphatase activi...

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Bibliographic Details
Published in:FEMS microbiology letters 2003-03, Vol.220 (2), p.197-206
Main Authors: Fernandes, Eloise Cedro, José Mauro Granjeiro, Eulázio Mikio Taga, Meyer-Fernandes, José Roberto, Aoyama, Hiroshi
Format: Article
Language:English
Subjects:
Acid phosphatase
Ascorbic acid
Calcium
Calcium ions
Carbon dioxide
Cell surface
Cobalt
Electrophoresis
Gel electrophoresis
Hydrogen peroxide
Iron
Kinases
Magnesium
Microbiology
Okadaic acid
p-Nitrophenylphosphate
Parasites
Phosphatase
Phosphoserine
Phosphotyrosine
Protozoa
Purification
Substrates
Trypanosoma brucei
Vanadate
Vanadates
Zinc
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Summary:Procyclic forms of Trypanosoma brucei possess a phosphatase activity on their external cell surface. This activity, while it dephosphorylates [32P]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 Km value of 0.29 mM with pNPP and was insensitive to the Fe2+/H2O2/ascorbate system.
ISSN:0378-1097
1574-6968
DOI:10.1016/S0378-10970300091-0