title: Purification and characterization of two extracellular polyhydroxyalkanoate depolymerases from Pseudomonas mendocina.
abstract: Two polyhydroxyalkanoate depolymerases, PHAase I and PHAase II, were purified to homogeneity from the culture supernatant of an effective PHA-degrading bacterium, Pseudomonas mendocina DS04-T. The molecular masses of PHAase I and PHAase II were determined by SDS-PAGE as 59.4 and 33.8 kDa, respectively. Their optimum pH values were 8.5 and 8, respectively. Enzymatic activity was optimal at 50 °C. Both purified enzymes could degrade PHB, PHBV, and P(3HB-co-4HB). Addition of Na(+) and K(+) slightly increased the rate of PHAase II. EDTA significantly inhibited PHAase II but not PHAase I. Mercaptoethanol and H2O2 also inhibited the activities of both enzymes.
authors.affiliation: School of Environmental and Biological Engineering, Liaoning Shihua University, Fushun, 113001, China.
authors.forename: Hailong
authors.initials: H
authors.lastname: Mao
authors.forename: Husheng
authors.initials: H
authors.lastname: Jiang
authors.forename: Tingting
authors.initials: T
authors.lastname: Su
authors.forename: Zhanyong
authors.initials: Z
authors.lastname: Wang
mesh_terms: D002265:Carboxylic Ester Hydrolases / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*; D004492:Edetic Acid / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D020536:Enzyme Activators; D004791:Enzyme Inhibitors / Q000378:metabolism; D004795:Enzyme Stability; D006861:Hydrogen Peroxide / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008623:Mercaptoethanol / Q000378:metabolism; D008970:Molecular Weight; D011188:Potassium / Q000378:metabolism; D044203:Pseudomonas mendocina / Q000201:enzymology*; D012964:Sodium / Q000378:metabolism; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D020536:Enzyme Activators; D004791:Enzyme Inhibitors; D008623:Mercaptoethanol; D004492:Edetic Acid; D012964:Sodium; D006861:Hydrogen Peroxide; D002265:Carboxylic Ester Hydrolases; C077226:poly(3-hydroxyalkanoic acid) depolymerase; D011188:Potassium