title: Characterization of an extracellular medium-chain-length poly(3-hydroxyalkanoate) depolymerase from Streptomyces sp. KJ-72.
abstract: A bacterial strain capable of degrading medium-chain-length polyhydroxyalkanoates (MCL-PHAs) was isolated from a soil sample. This organism, which was identified as Streptomyces sp. KJ-72, secreted MCL-PHA depolymerase into the culture fluid only when it was cultivated on MCL-PHAs. The extracellular MCL-PHA depolymerase of the organism was purified to electrophoretic homogeneity by ion exchange column chromatography and gel filtration. The enzyme consisted of a monomeric subunit having a molecular mass of 27.1 kDa and isoelectric point of 4.7. The maximum activity was observed at pH 8.7 and 50 degrees C. The enzyme was sensitive to N-bromosuccinimide and acetic anhydride, indicating the presence of tryptophan and lysine residues in the catalytic domain. The enzyme was able to hydrolyze various chain-length p-nitrophenyl esters of fatty acids and polycaprolactone as well as various types of MCL-PHAs. However, lipase activity of the enzyme was not detected. The main hydrolysis product of poly(3-hydroxyheptanoate) was identified to be the dimer of 3-hydroxyheptanoate.
authors.affiliation: Department of Microbiology, Chungnam National University, Daejeon 305-764, Korea.
authors.forename: Hwa Jung
authors.initials: HJ
authors.lastname: Kim
authors.forename: Do Young
authors.initials: DY
authors.lastname: Kim
authors.forename: Jin Sik
authors.initials: JS
authors.lastname: Nam
authors.forename: Kyung Sook
authors.initials: KS
authors.lastname: Bae
authors.forename: Young Ha
authors.initials: YH
authors.lastname: Rhee
mesh_terms: D002265:Carboxylic Ester Hydrolases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D003470:Culture Media; D004275:DNA, Ribosomal / Q000032:analysis; D008969:Molecular Sequence Data; D011091:Polyesters / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology; D013302:Streptomyces / Q000145:classification / Q000201:enzymology* / Q000235:genetics; D013379:Substrate Specificity
chemical_list: D003470:Culture Media; D004275:DNA, Ribosomal; D011091:Polyesters; D012336:RNA, Ribosomal, 16S; D002265:Carboxylic Ester Hydrolases; C077226:poly(3-hydroxyalkanoic acid) depolymerase