Mycelial forms of <Emphasis Type="Italic">Pseudallescheria boydii</Emphasis> present ectophosphatase activities |
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Authors: | Tina Kiffer-Moreira Ana Acacia S Pinheiro Márcia R Pinto Fabiano F Esteves Thais Souto-Padrón Eliana Barreto-Bergter José R Meyer-Fernandes |
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Institution: | (1) Instututo de Bioquímica Médica, Universidade Federal do Rio de Janeiro, CCS, bloco H, Cidade Universitária, Rio de Janeiro, RJ, 21941-590, Brazil;(2) Instituto de Microbiologia Prof. Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21941-590, Brazil |
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Abstract: | Phosphatase activities were characterized in intact mycelial forms of Pseudallescheria boydii, which are able to hydrolyze the artificial substrate p-nitrophenylphosphate (p-NPP) to p-nitrophenol (p-NP) at a rate of 41.41 ± 2.33 nmol p-NP per h per mg dry weight, linearly with increasing time and with increasing cell density.
MgCl2, MnCl2 and ZnCl2 were able to increase the (p-NPP) hydrolysis while CdCl2 and CuCl2 inhibited it. The (p-NPP) hydrolysis was enhanced by increasing pH values (2.5-8.5) over an approximately 5-fold range. High sensitivity to specific
inhibitors of alkaline and acid phosphatases suggests the presence of both acid and alkaline phosphatase activities on P. boydii mycelia surface. Cytochemical localization of the acid and alkaline phosphatase showed electron-dense cerium phosphate deposits
on the cell wall, as visualized by electron microscopy. The product of p-NPP hydrolysis, inorganic phosphate (Pi), and different inhibitors for phosphatase activities inhibited p-NPP hydrolysis in a dose-dependent manner, but only the inhibition promoted by sodium orthovanadate and ammonium molybdate
is irreversible. Intact mycelial forms of P. boydii are also able to hydrolyze phosphoaminoacids with different specificity. |
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Keywords: | Pseudallescheria boydii Phosphatase activities Ecto-enzymes |
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