title: Leishmania amazonensis: characterization of an ecto-pyrophosphatase activity.
abstract: Several ecto-enzymatic activities have been described in the plasma membrane of the protozoan Leishmania amazonensis, which is the major etiological agent of diffuse cutaneous leishmaniasis in South America. These enzymes, including ecto-phosphatases, contribute to the survival of the parasite by participating in phosphate metabolism. This work identifies and characterizes the extracellular hydrolysis of inorganic pyrophosphate related to an ecto-pyrophosphatase activity of the promastigote form of L. amazonensis. This ecto-pyrophosphatase activity is insensitive to MnCl2 but is strongly stimulated by MgCl2. This stimulation was not observed during the hydrolysis of p-nitrophenyl phosphate (p-NPP) or β-glycerophosphate, two substrates for different ecto-phosphatases present in the L. amazonensis plasma membrane. Furthermore, extracellular PPi hydrolysis is more efficient at alkaline pHs, while p-NPP hydrolysis occurs mainly at acidic pHs. These results led us to conclude that extracellular PPi is hydrolyzed not by non-specific ecto-phosphatases but rather by a genuine ecto-pyrophosphatase. In the presence of 5mM MgCl2, the ecto-pyrophosphatase activity from L. amazonensis is sensitive to micromolar concentrations of NaF and millimolar concentrations of CaCl2. Moreover, this activity is significantly higher during the first days of L. amazonensis culture, which suggests a possible role for this enzyme in parasite growth.
authors: Instituto de Bioquímica Médica, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, 21941-590 Rio de Janeiro, RJ, Brazil; Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem, 21941-590 Rio de Janeiro, RJ, Brazil.
authors: Anita Leocadio
authors: AL
authors: Freitas-Mesquita
authors: Laboratório de Terapia e Fisiologia Celular e Molecular, Centro Universitário Estadual da Zona Oeste, 23070-200 Rio de Janeiro, RJ, Brazil.
authors: André Luiz
authors: AL
authors: Fonseca-de-Souza
authors: Instituto de Bioquímica Médica, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, 21941-590 Rio de Janeiro, RJ, Brazil; Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem, 21941-590 Rio de Janeiro, RJ, Brazil. Electronic address: meyer@bioqmed.ufrj.br.
authors: José Roberto
authors: JR
authors: Meyer-Fernandes
mesh_terms: D000818:Animals; D002122:Calcium Chloride / Q000494:pharmacology; D002462:Cell Membrane / Q000201:enzymology; D002712:Chlorides / Q000494:pharmacology; D006224:Cricetinae; D011756:Diphosphates / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007894:Leishmania mexicana / Q000201:enzymology* / Q000254:growth & development; D016774:Leishmaniasis, Diffuse Cutaneous / Q000469:parasitology; D007978:Levamisole / Q000494:pharmacology; D015636:Magnesium Chloride / Q000494:pharmacology; D017895:Manganese Compounds / Q000494:pharmacology; D011755:Pyrophosphatases / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism*; D012969:Sodium Fluoride / Q000494:pharmacology; D013644:Tartrates / Q000494:pharmacology; D014638:Vanadates / Q000494:pharmacology
chemical_list: D002712:Chlorides; D011756:Diphosphates; D017895:Manganese Compounds; D013644:Tartrates; D015636:Magnesium Chloride; D007978:Levamisole; D014638:Vanadates; C107241:diphosphoric acid; D012969:Sodium Fluoride; D011755:Pyrophosphatases; D002122:Calcium Chloride; C025340:manganese chloride; C029768:tartaric acid
keywords: Ecto-PPase; Ecto-pyrophosphatase; Inorganic pyrophosphate; Leishmania amazonensis; PPase; PPi; Pi; ecto-pyrophosphatase; inorganic phosphate; pyrophosphatase; pyrophosphate; sPPase; soluble pyrophosphatase