title: Isolation and general characterization of a heat-stable proteinase from Pseudomonas fluorescens aft 36.
abstract: An extracellular proteinase from Pseudomonas fluorescens, strain AFT 36, was isolated to homogeneity by chromatography on DEAE-cellulose and Sephadex G-150; a 230-fold increase in specific activity with a recovery of 53% was obtained. The enzyme was optimally active at pH 6.5 and 45 degrees C; activity declined rapidly at higher temperatures but significant activity persisted down to 4 degrees C. Activity was strongly inhibited by 10(-3) M EDTA and was partially restored by addition of Zn2+, Ca2+ or Co2+. The Km values on methylated casein and sodium caseinate were 18.2 and 7.1 mg/ml, respectively. The enzyme was very labile in phosphate buffer and in a mild salts buffer at 55 degrees C but was very stable in the latter at more than 80 degrees C.
mesh_terms: D002413:Cations, Divalent; D004492:Edetic Acid / Q000494:pharmacology; D007700:Kinetics; D008670:Metals / Q000494:pharmacology; D010447:Peptide Hydrolases / Q000302:isolation & purification* / Q000378:metabolism; D011549:Pseudomonas / Q000201:enzymology; D011551:Pseudomonas fluorescens / Q000201:enzymology*; D013045:Species Specificity
chemical_list: D002413:Cations, Divalent; D008670:Metals; D004492:Edetic Acid; D010447:Peptide Hydrolases