title: Purification and characterization of an intracellular aspartyl acid proteinase (pumAi) from Ustilago maydis.
abstract: The intracellular proteinase pumAi in Ustilago maydis has been associated with yeast-mycelium dimorphic transition. The proteinase was purified from a cell-free extract by ammonium sulfate fractionation and chromatographic steps including hydrophobic interactions on a Phenyl Superose column, ion exchange on a Mono Q column, and gel filtration on Superose 12 columns. The enzyme has a mass of 35.3-36.6 kDa, a pH and temperature optimum of 4.0 and 40 degrees C, respectively, and a pI of 5.5. The enzyme degraded hemoglobin, gelatin, albumin, and casein, but not collagen, and the enzymatic activity was strongly inhibited by pepstatin A, an aspartyl proteinase-specific inhibitor. The biochemical characteristics of pumAi are similar to other fungal intracellular aspartyl proteinases, however, this is the first biochemical characterization of a basidiomycete proteinase probably associated with dimorphic yeast-mycelium transition.
authors.affiliation: Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, I.P.N, Mexico.
authors.forename: Yuridia
authors.initials: Y
authors.lastname: Mercado-Flores
authors.forename: Adriana
authors.initials: A
authors.lastname: Trejo-Aguilar
authors.forename: Bernardo
authors.initials: B
authors.lastname: Ramírez-Zavala
authors.forename: Lourdes
authors.initials: L
authors.lastname: Villa-Tanaca
authors.forename: César
authors.initials: C
authors.lastname: Hernández-Rodríguez
mesh_terms: D016282:Aspartic Acid Endopeptidases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D011480:Protease Inhibitors / Q000494:pharmacology; D013379:Substrate Specificity; D013696:Temperature; D014588:Ustilago / Q000201:enzymology* / Q000502:physiology*
chemical_list: D011480:Protease Inhibitors; D016282:Aspartic Acid Endopeptidases