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3-Hydroxybutyric Acid

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Yoshiharu Doi – One of the best experts on this subject based on the ideXlab platform.

  • Dual biosyntheses of poly[(R)-3-Hydroxybutyric Acid] and silk protein for the fabrication of biofunctional bioplastic
    Polymer Journal, 2011
    Co-Authors: Keiji Numata, Yoshiharu Doi
    Abstract:

    This is the first report on dual synthesis of poly[( R )-3-Hydroxybutyric Acid] (PHB) and protein polymer by recombinant microorganisms for use in the fabrication of a biofunctional PHB-based material hybridized with functional proteins. PHB and recombinant silk protein, a model protein developed in this study, were synthesized by a recombinant Escherichia coli system, and then films of PHB hybridized with the silk protein (PHB/Silk) were prepared. The presence of the silk protein in the amorphous phase of the PHB/Silk film was demonstrated based on wide-angle X-ray diffraction and differential scanning calorimetry measurements, which also revealed the enhanced tensile strength and elongation at break of the PHB/Silk film. The cell adhesion of human mesenchymal stem cells (hMSCs) for the PHB/Silk film increased because of the addition of silk molecules to the film. This might have been because the silk molecules existed in the amorphous phase at the surface of the PHB/Silk films, and were exposed to hMSCs. The overall results illustrate the potential of this dual synthesis system as a versatile and useful platform method for preparation of biofunctional PHB-based materials, especially for biomedical applications. This is the first report on dual synthesis of poly[( R )-3-Hydroxybutyric Acid] (PHB) and silk proteins by recombinant microorganisms for use in the fabrication of a biofunctional PHB-based material hybridized with functional proteins. The overall results illustrate the potential of this dual synthesis system as a versatile and useful platform method for preparation of biofunctional PHB-based materials, especially for biomedical applications.

  • effects of residual metal compounds and chain end structure on thermal degradation of poly 3 hydroxybutyric Acid
    Polymer Degradation and Stability, 2006
    Co-Authors: Kang Ju Kim, Yoshiharu Doi, Hideki Abe
    Abstract:

    Abstract Thermal degradation behaviours of poly(3-Hydroxybutyric Acid) (P(3HB); bacterial poly[( R )-3-Hydroxybutyric Acid] and synthetic poly[( R , S )-3-Hydroxybutyric Acid] samples, were examined under both isothermal and non-isothermal conditions. The inverse of number-average degree of polymerisation for all P(3HB) samples decreased linearly with degradation time during the initial stage of isothermal degradation at a temperature ranging from 170–190 °C. In addition, crotonyl unit was detected in the residual polymer samples as main ω-chain-end. These results indicate that the dominant thermal degradation reaction for P(3HB) is a random chain scission via cis -elimination reaction of P(3HB) molecules. It was found that the presence of either Ca or Mg ions enhances the depolymerisation of P(3HB) molecules, while that Zn ions hardly catalyse the reaction. As a result, a shift of thermogravimetric curves toward the lower temperature regions was observed for the P(3HB) samples containing high amounts of Ca and Mg compounds.

  • Enzymatic degradation processes of poly[(R)-3-Hydroxybutyric Acid] and poly[(R)-3-Hydroxybutyric Acid-co-(R)-3-hydroxyvaleric Acid] single crystals revealed by atomic force microscopy: effects of molecular weight and second-monomer composition on ero
    Biomacromolecules, 2005
    Co-Authors: Keiji Numata, Yoshiharu Doi, Yoshihiro Kikkawa, Tadahisa Iwata, Takeharu Tsuge, Hideki Abe
    Abstract:

    Enzymatic degradation processes of poly[(R)-3-Hydroxybutyric Acid] (P(3HB)) and poly[(R)-3-Hydroxybutyric Acid-co-(R)-3-hydroxyvaleric Acid] (P(3HB-co-3HV)) single crystals in the presence of PHB depolymerase from Ralstonia pickettii T1 were studied by real-time and static atomic force microscopy (AFM) observations. Fibril-like crystals were generated along the long axis of single crystals during the enzymatic degradation, and then the dimensions of fibril-like crystals were analyzed quantitatively. The morphologies and sizes of fibril-like crystals were dependent on the molecular weight and copolymer composition of polymers. For all samples, the crystalline thickness gradually decreased toward a tip from the root of a fibril-like crystal after enzymatic degradation for 1 h. The thinning of fibril-like crystals may be attributed to the destruction of chain-packing structure toward crystallographic c axis by the adsorption of enzyme. From the real-time AFM images, it was found that at the initial stage of degradation the enzymatic erosion started from the disordered chain-packing region in single crystals to form the grooves along the a axis. The generated fibril-like crystals deformed at a constant rate along the a axis with a constant rate after the induction time. The erosion rate at the grooves along the a axis increased with a decrease of molecular weight and with an increase of copolymer composition. On the other hand, the erosion rate along the a axis, at the tip of the fibril-like crystal, was dependent on only the copolymer composition, and the value increased with an increase in the copolymer composition. The morphologies and sizes of fibril-like crystals were governed by both the erosion rates along the a axis at the grooves and tip of fibril-like crystals. In addition, we were able to estimated the overall enzymatic erosion rate of single crystals by PHB depolymerase from the volumetric analysis.

Yoshio Inoue – One of the best experts on this subject based on the ideXlab platform.

  • Crystal morphologies and enzymatic degradation of melt-crystallized thin films of random copolyesters of (R)-3-Hydroxybutyric Acid with (R)-3-hydroxyalkanoic Acids
    Polymer Degradation and Stability, 2002
    Co-Authors: Yoshihiro Kikkawa, Hideki Abe, Yoshio Inoue, Tadahisa Iwata, Yoshiharu Doi
    Abstract:

    Abstract Spherulitic and lamellar morphologies of melt-crystallized thin films for poly[( R )-3-Hydroxybutyric Acid– co -16 mol%-( R )-3-hydroxypentanoic Acid] and poly[( R )-3-Hydroxybutyric Acid– co -8 mol%-( R )-3-hydroxyhexanoic Acid] were characterized by optical, transmission electron and atomic force microscopies. Two-dimensional spherulites were formed throughout the thin films of bacterial copolymers after isothermal crystallization at 110 °C. The second monomer units in the random copolymer chains were excluded from the crystalline regions of poly[( R )-3-Hydroxybutyric Acid] (P[( R )-3HB]) lamellar crystals during isothermal crystallization process. Formation of the thin crystals with 5–7 nm thickness was found on the surface of original lamellar crystals with 10–13 nm thickness in the course of storage at room temperature after isothermal crystallization at 110 °C. Both the thermal analysis and morphological observation of copolymer thin films suggest that a certain sequential length of ( R )-3HB units in copolymer is needed for the formation of the original lamellar crystals at a crystallization temperature. The enzymatic degradation of copolymer thin films was performed in an aqueous solution of PHB depolymerase from Ralstonia pickettii . At the initial stage of enzymatic degradation, only the thin crystals formed at room temperature were eroded by the enzyme. By the continuous degradation reaction, the original thick lamellar crystals showed a comb-like texture and grooves along the crystal growth direction, suggesting that disordered chain-packing regions are accumulated in the original lamellar crystals during crystal growth process.

  • Real‐time enzymatic degradation study of poly[(R)‐3‐hydroxybutyric Acid] copolymer thin film by atomic force microscopy in buffer solution
    Macromolecular Bioscience, 2002
    Co-Authors: Yoshihiro Kikkawa, Hideki Abe, Yoshio Inoue, Tadahisa Iwata, Tomohide Murase, Yoshiharu Doi
    Abstract:

    In situ observation of lamellar crystals during the enzymatic degradation by poly(hydroxybytyrate) PHB depolymerase is carried out on the thin films of poly[((R)-3-Hydroxybutyric Acid)-co-(16 mol-%-(R)-3-hydroxypentanoic Acid)] using atomic force microscopy in buffer solution. Erosion of lamellar crystals and formation of splintered morphology along the crystal growth direction are directly observed during the course of the enzymatic degradation process. The changes in lamellar morphologies caused by enzymatic degradation are discussed in terms of lamellar crystal growth process.

  • Real-time enzymatic degradation study of poly[(R)-3-Hydroxybutyric Acid] copolymer thin film by atomic force microscopy in buffer solution
    Macromolecular Chemistry and Physics, 2002
    Co-Authors: Yoshihiro Kikkawa, Hideki Abe, Yoshio Inoue, Tadahisa Iwata, Tomohide Murase, Yoshiharu Doi
    Abstract:

    Communication: In situ observation of lamellar crystals during the enzymatic degradation by poly(hydroxybutyrate) (PHB) depolymerase is carried out on the thin films of poly[((R)-3-Hydroxybutyric Acid)-co-(16 mol-%-(R)-3-hydroxypentanoic Acid)] using atomic force microscopy in buffer solution. Erosion of lamellar crystals and formation of splintered morphology along the crystal growth direction are directly observed during the course of the enzymatic degradation process. The changes in lamellar morphologies caused by enzymatic degradation are discussed in terms of lamellar crystal growth process.

Hideki Abe – One of the best experts on this subject based on the ideXlab platform.

  • effects of residual metal compounds and chain end structure on thermal degradation of poly 3 hydroxybutyric Acid
    Polymer Degradation and Stability, 2006
    Co-Authors: Kang Ju Kim, Yoshiharu Doi, Hideki Abe
    Abstract:

    Abstract Thermal degradation behaviours of poly(3-Hydroxybutyric Acid) (P(3HB); bacterial poly[( R )-3-Hydroxybutyric Acid] and synthetic poly[( R , S )-3-Hydroxybutyric Acid] samples, were examined under both isothermal and non-isothermal conditions. The inverse of number-average degree of polymerisation for all P(3HB) samples decreased linearly with degradation time during the initial stage of isothermal degradation at a temperature ranging from 170–190 °C. In addition, crotonyl unit was detected in the residual polymer samples as main ω-chain-end. These results indicate that the dominant thermal degradation reaction for P(3HB) is a random chain scission via cis -elimination reaction of P(3HB) molecules. It was found that the presence of either Ca or Mg ions enhances the depolymerisation of P(3HB) molecules, while that Zn ions hardly catalyse the reaction. As a result, a shift of thermogravimetric curves toward the lower temperature regions was observed for the P(3HB) samples containing high amounts of Ca and Mg compounds.

  • Enzymatic degradation processes of poly[(R)-3-Hydroxybutyric Acid] and poly[(R)-3-Hydroxybutyric Acid-co-(R)-3-hydroxyvaleric Acid] single crystals revealed by atomic force microscopy: effects of molecular weight and second-monomer composition on ero
    Biomacromolecules, 2005
    Co-Authors: Keiji Numata, Yoshiharu Doi, Yoshihiro Kikkawa, Tadahisa Iwata, Takeharu Tsuge, Hideki Abe
    Abstract:

    Enzymatic degradation processes of poly[(R)-3-Hydroxybutyric Acid] (P(3HB)) and poly[(R)-3-Hydroxybutyric Acid-co-(R)-3-hydroxyvaleric Acid] (P(3HB-co-3HV)) single crystals in the presence of PHB depolymerase from Ralstonia pickettii T1 were studied by real-time and static atomic force microscopy (AFM) observations. Fibril-like crystals were generated along the long axis of single crystals during the enzymatic degradation, and then the dimensions of fibril-like crystals were analyzed quantitatively. The morphologies and sizes of fibril-like crystals were dependent on the molecular weight and copolymer composition of polymers. For all samples, the crystalline thickness gradually decreased toward a tip from the root of a fibril-like crystal after enzymatic degradation for 1 h. The thinning of fibril-like crystals may be attributed to the destruction of chain-packing structure toward crystallographic c axis by the adsorption of enzyme. From the real-time AFM images, it was found that at the initial stage of degradation the enzymatic erosion started from the disordered chain-packing region in single crystals to form the grooves along the a axis. The generated fibril-like crystals deformed at a constant rate along the a axis with a constant rate after the induction time. The erosion rate at the grooves along the a axis increased with a decrease of molecular weight and with an increase of copolymer composition. On the other hand, the erosion rate along the a axis, at the tip of the fibril-like crystal, was dependent on only the copolymer composition, and the value increased with an increase in the copolymer composition. The morphologies and sizes of fibril-like crystals were governed by both the erosion rates along the a axis at the grooves and tip of fibril-like crystals. In addition, we were able to estimated the overall enzymatic erosion rate of single crystals by PHB depolymerase from the volumetric analysis.

  • Crystal morphologies and enzymatic degradation of melt-crystallized thin films of random copolyesters of (R)-3-Hydroxybutyric Acid with (R)-3-hydroxyalkanoic Acids
    Polymer Degradation and Stability, 2002
    Co-Authors: Yoshihiro Kikkawa, Hideki Abe, Yoshio Inoue, Tadahisa Iwata, Yoshiharu Doi
    Abstract:

    Abstract Spherulitic and lamellar morphologies of melt-crystallized thin films for poly[( R )-3-Hydroxybutyric Acid– co -16 mol%-( R )-3-hydroxypentanoic Acid] and poly[( R )-3-Hydroxybutyric Acid– co -8 mol%-( R )-3-hydroxyhexanoic Acid] were characterized by optical, transmission electron and atomic force microscopies. Two-dimensional spherulites were formed throughout the thin films of bacterial copolymers after isothermal crystallization at 110 °C. The second monomer units in the random copolymer chains were excluded from the crystalline regions of poly[( R )-3-Hydroxybutyric Acid] (P[( R )-3HB]) lamellar crystals during isothermal crystallization process. Formation of the thin crystals with 5–7 nm thickness was found on the surface of original lamellar crystals with 10–13 nm thickness in the course of storage at room temperature after isothermal crystallization at 110 °C. Both the thermal analysis and morphological observation of copolymer thin films suggest that a certain sequential length of ( R )-3HB units in copolymer is needed for the formation of the original lamellar crystals at a crystallization temperature. The enzymatic degradation of copolymer thin films was performed in an aqueous solution of PHB depolymerase from Ralstonia pickettii . At the initial stage of enzymatic degradation, only the thin crystals formed at room temperature were eroded by the enzyme. By the continuous degradation reaction, the original thick lamellar crystals showed a comb-like texture and grooves along the crystal growth direction, suggesting that disordered chain-packing regions are accumulated in the original lamellar crystals during crystal growth process.