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Plasticization of poly(hydroxybutyrate) in vivo
S T Harrison1, H A Chase, S R Amor
1Department of Chemical Engineering, University of Cambridge, UK.
International Journal of Biological Macromolecules
|February 1, 1992
Summary
Water plasticizes poly(hydroxybutyrate) (PHB) in vivo, making it susceptible to depolymerases. Other treatments alter PHB mobility and crystallinity, affecting its biological activity.
Area of Science:
- Biochemistry
- Polymer Science
- Microbiology
Background:
- Poly(hydroxybutyrate) (PHB) is a biopolymer produced by microorganisms.
- Understanding PHB's physical state is crucial for its biological function and degradation.
Purpose of the Study:
- To investigate the effects of various treatments on PHB mobility and crystallinity in whole cells and native granules.
- To correlate these physical changes with biological activity and susceptibility to depolymerases.
Main Methods:
- 13C-n.m.r. spectroscopy to assess PHB mobility.
- X-ray powder diffraction to determine PHB crystallinity.
- Correlation with known biological effects of treatments.
Main Results:
- Water acts as a plasticizer for PHB in vivo, enhancing its susceptibility to depolymerases.
- Freeze-drying induces a partially-immobilized amorphous state, reversible by rehydration.
- Centrifugation or hydrophobic detergent treatment leads to a crystalline state, reducing depolymerase susceptibility.
- Heating or refrigeration inactivates granules, likely due to membrane/protein damage.
Conclusions:
- PHB plasticization in vivo is primarily mediated by water.
- Only mobile PHB is effectively degraded by depolymerases.
- Granule treatments can induce distinct physical states affecting biological competence.