title: Formation and properties of L-glutaminase and L-asparaginase activities in Pichia polymorpha.
abstract: An ascogenous yeast with high potentialities for L-glutaminase and L-asparaginase formation was isolated from Egyptian soils by the application of the culture enrichment method. The organism, identified as Pichia polymorpha, was obtained through the enrichment of soil samples with a simple medium containing 0.5% L-glutaminase as a major carbon and nitrogen source at low pH values. The amidase activities were produced constitutively on a variety of media irrespective of the presence of their substrates in the growth medium. Assays of enzyme activity have revealed that optimum pH values for L-glutamine and L-asparagine hydrolysis are 6.0 and 6.7, respectively. The L-asparaginase activity of the cells was heat-stable for at least 10 minutes at 60 degrees C. The enzyme exhibited apparent Km of 1.37 x 10(-2) M and 1.95 x 10(-2) M for L-asparagine and L-glutamine, respectively. No metal requirement were detected for the amidase activities of the organism under study.
mesh_terms: D001203:Ascomycota / Q000201:enzymology*; D001215:Asparaginase / Q000378:metabolism*; D001216:Asparagine / Q000378:metabolism; D002413:Cations, Divalent / Q000494:pharmacology; D004790:Enzyme Induction; D005972:Glutaminase / Q000378:metabolism*; D005973:Glutamine / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D010843:Pichia / Q000201:enzymology*; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D002413:Cations, Divalent; D005973:Glutamine; D001216:Asparagine; D001215:Asparaginase; D005972:Glutaminase