Plasticization of poly(hydroxybutyrate) in vivo

• Published in: International journal of biological macromolecules Vol. 14; no. 1; pp. 50 - 56
• Main Authors: Harrison, Susan T.L., Chase, Howard A., Amor, Stuart R., Bonthrone, Karen M., Sanders, Jeremy K.M.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.02.1992; Elsevier Science
• Subjects: Alcaligenes - growth & development; Alcaligenes - metabolism; Bacteriology; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Granule structure; Hydrolases; Hydroxybutyrates - chemistry; Magnetic Resonance Spectroscopy - methods; Metabolism. Enzymes; Microbiology; Molecular Conformation; n.m.r; plasticization; poly(hydroxybutyrate); Polyesters - chemistry; X-ray diffraction; X-Ray Diffraction - methods; X-ray diffraction; Granule structure; poly(hydroxybutyrate); n.m.r; plasticization; Alcaligenes eutrophus; Reaction intermediate; In vivo; Bacteria; Butyrate(hydroxy)polymer; Biosynthesis; Models; NMR spectrometry; Metabolism; X ray diffraction; Plasticization
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/S0141-8130(05)80020-0

The influence of a variety of treatments on the mobility and crystallinity of poly(hydroxybutyrate) (PHB) in whole cells and native granules has been probed using 13 C-n.m.r. spectroscopy and X-ray powder diffraction, and correlated with the known biological effects of these treatments. It was concluded that at least water is responsible for PHB plasticization in vivo, and that only native mobile PHB is susceptible to deploymerases. Another, probably hydrophobic, component appears to be involved either as plasticizer or nucleation inhibitor. Three states of the granule are identified in addition to the native, biologically-competent state: freeze-drying of whole cells leads to a partially-immobilized amorphous state which can be restored virtually to native mobility by rehydration; extended centrifugation of native granules in aqueous suspension, or treatment with hydrophobic detergents under certain conditions, leads to a crystalline state that is less susceptible to exogenous depolymerase; and heating to 95°C or refrigeration has no detectable effect on mobility but leads to inactivation of the granule, presumably via damage to superficial membrane or protein.