Characterization of an extracellular medium-chain-length poly(3-hydroxyalkanoate) depolymerase from Streptomyces sp. KJ-72 |
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Authors: | Kim Hwa Jung Kim Do Young Nam Jin Sik Bae Kyung Sook Rhee Young Ha |
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Institution: | (1) Department of Microbiology, Chungnam National University, Daejeon, 305-764, Korea;(2) Korea Research Institute of Bioscience and Biotechnology, Daejeon, 305-600, Korea |
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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 °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.
This revised version was published online in June 2006 with corrections to the Cover Date. |
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Keywords: | Medium-chain-length polyhydroxyalkanoate Polyhydroxyalkanoate depolymerase Streptomyces sp KJ-72 |
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