1989 Fiscal Year Final Research Report Summary
Degradation of plastics by microbial enzyme
| Project/Area Number |
63571038
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Biological pharmacy
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| Research Institution | Kanagawa University (1989)
Kyoto University (1988) |
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Principal Investigator |
SAITO Terumi Kanagawa Univ. School of Science Professor, 理学部, 教授 (80025717)
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| Co-Investigator(Kenkyū-buntansha) |
ICHIKAWA Atsushi Kyoto Univ. Facul. of Pharm. Professor, 薬学部, 教授 (10025695)
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| Project Period (FY) |
1988 – 1989
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| Keywords | Poly(3-hydroxybutyrate) / PHB / Poly-beta-hydroxybutyrate / Biopolymer / Esterase / Biodegradable polymer / Alcaligenes faecalis / Extracellular enzyme |
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| Research Abstract |
1. The Poly-3-hydroxybutyrate (PHB) recognition site of PHB depolymerase of Alcaligenes faecalis T1: When the PHB depolynerase was treated with trypsin, the molecular mass was changed from 47 KDa to 42 KDa in accordance with the decrease of hydrophobicity of the enzyme molecule. At the same time, the trypsintreated enzyme lost PHB-hydrolyzing activity but it maintained 3-hydroxybutyrate trimer-hydrolyzing activity. On the other hand, diisopropylfluorophosphate- treated enzyme, which has neither PHB- nor trimer-hydrolyzing activity, still had the binding capacity to PHB granules. These results indicate that there is a specific site in the PHB depolymerase which recognizes PHB surface. The gene of PHB depolymerase was cloned and sequenced. According to the deduced amino acid sequence, trypsin probably cuts at the first arginine from the C-terminus of the enzyme. Although there is a possibility that the 5 KDa fragment released by trypsin is a interface recognition site, we concluded that the interface recognition site of PHB depolymerase was sterically composed of several portions of peptide in the enzyme.
2. Cloning of the gene for 3-hydroxybutyrate oligoner hydrolase: In order to compare the structure of 3-hydroxybutyrate oligomer hydrolase to PHB depolymerase, the gene for the oligoner hydrolase was cloned. This work is under way.
3. Degradability of copolymer of 3-hydroxybutyrate by PHB depolymerase: Degradability of poly(3-hydroxybutyric acid (3HB)-co-3-hydroxyvaleric acid (3HV)) and poly(3HB-co-4-hydroxybutyric acid (4HB)) by PHB depolymerase was investigated. The rate of enzymatic surface erosion decreased in the order P(3HB-co-4HB) P(3HB) P(3HB-co-3HV).
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