title: Mycelial forms of Pseudallescheria boydii present ectophosphatase activities.
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.
authors: Instututo de Bioquímica Médica, Universidade Federal do Rio de Janeiro, CCS, bloco H, Cidade Universitária, Rio de Janeiro, RJ, 21941-590, Brazil.
authors: Tina
authors: T
authors: Kiffer-Moreira
authors: Ana Acacia S
authors: AA
authors: Pinheiro
authors: Márcia R
authors: MR
authors: Pinto
authors: Fabiano F
authors: FF
authors: Esteves
authors: Thais
authors: T
authors: Souto-Padrón
authors: Eliana
authors: E
authors: Barreto-Bergter
authors: José R
authors: JR
authors: Meyer-Fernandes
mesh_terms: D006863:Hydrogen-Ion Concentration; D025282:Mycelium / Q000201:enzymology*; D010744:Phosphoric Monoester Hydrolases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D011541:Pseudallescheria / Q000201:enzymology*; D013379:Substrate Specificity
chemical_list: D010744:Phosphoric Monoester Hydrolases