Nuclear magnetic resonance studies on bacterial copolyesters of 3‐hydroxybutyric acid and 3‐hydroxyvaleric acid

Doi, Yoshiharu; Kunioka, Masao; Tamaki, Akira; Nakamura, Yoshiyuki; Soga, Kazuo

doi:10.1002/macp.1988.021890512

Cited by 33 publications

(17 citation statements)

References 11 publications

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“…For both samples, the slope was between 0.5 and 0.6, indicating a random coil conformation in chloroform. These results are consistent with the results of Miyaki et al, 17 who found that indices for molar mass dependence of intrinsic viscosity and radius of gyration of PHB approached the limits for random coil molecular conformation in chloroform, and with the NMR results of Doi et al, 29 who showed that PHA molecules are flexible chains in chloroform.…”

Section: Resultssupporting

confidence: 93%

SEC-MALS Characterization of Microbial Polyhydroxyalkanoates

Žagar

Kržan

2004

Biomacromolecules

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Characterization of poly-3-hydroxybutyric acid (PHB) and poly-3-hydroxybutyric-co-valeric acid (PHBV, 13% valerate) in chloroform was performed using size exclusion chromatography coupled to a multi-angle light scattering detector (SEC-MALS). Absolute molar mass averages, molar mass distribution, and the radius of gyration were determined. Three sample preparation methods were examined: dissolution in chloroform (1) at room temperature, (2) at 60 degrees C, and (3) after thermal pretreatment of samples (annealing at 180 degrees C with subsequent quenching in liquid nitrogen). Dissolution at 60 degrees C and dissolution of thermally pretreated samples gave molecularly dissolved PHB and PHBV. At 60 degrees C using acid free chloroform, there was no indication of degradation for up to 120 min dissolution time, whereas thermal degradation of polymers did take place during annealing at 180 degrees C. The degradation rate constants for number and weight average degree of polymerization at 180 degrees C were slightly higher for PHB (5.19 x 10(-5) min(-1), 4.95 x 10(-5) min(-1)) than for PHBV (4.99 x 10(-5) min(-1), 4.54 x 10(-5) min(-1)). The dependence of the radii of gyration on molar mass showed that both polymers form random coils in chloroform. The relationship between the absolute molar masses and relative SEC results was determined. DSC and NMR characterization also gave evidence of the progress of degradation.

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Section: Resultssupporting

confidence: 93%

SEC-MALS Characterization of Microbial Polyhydroxyalkanoates

Žagar

Kržan

2004

Biomacromolecules

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“…Figure 1 shows the 500-MHz 'H NMR spectrum of PHB at 27 "C. The assignments of the signals have been reported. 15 The conformational structure around the CH,-CH bond in solution can be determined by the analysis of the methylene proton resonances. The methylene protons (HA, HB) spin-couple to the methine proton (Hx), forming an ABX-type three-spin system.…”

Section: Resultsmentioning

confidence: 99%

Conformational analysis of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) in solution by proton NMR spectroscopy

Kamiya¹,

Inoue²,

Yamamoto³

et al. 1990

Macromolecules

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It has been found that 3-hydroxybutyrate homopolymer (PHB) and its copolymers with 3-hydroxyvalerate (PHB-HV) are accumulated in some microorganisms. In this paper the conformational aspects of PHB and PHB-HV in chloroform were investigated on the basis of the vicinal coupling constants of the ' H NMR spectrum. The two methylene proton resonances of PHB were assigned by using the two-dimensional 'H-'H NOESY spectrum. The fractional populations of gauche and trans conformers around the main-chain CH-CH, bond are estimated to be 0.6 and 0.4, respectively. The main-chain methylene resonances of PHB-HV are split by two factors, Le., by the ABX spin-spin coupling between the methylene and methine protons and by the difference in the diad and/or triad monomer sequences. By separating these splitting factors, with the aid of the 'H-13C COSY spectra, the conformational structures of PHB-HV were determined. In every diad and/or triad monomer sequence, the fractional populations of gauche and trans conformers around the main-chain CH-CH, bond are also believed to be 0.6 and 0.4, respectively. It was confirmed that two kinds of monomer units, HB and HV, in PHB-HV assume almost the same conformation irrespective of HV mole fractions in chloroform solution. This result suggests the possibility that PHB-HV's with different HV mole fraction form isomorphic crystals.

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“…Culture condition and media: A. eutrophus was cultured in NR medium (polypeptone, 10 g/l; yeast extract, 10 g/l; beef extract 5 g/l; and ammonium sulfate 5 g/l, pH 7.0) (Sambrook et al, 1989) and E. coli strain was grown in LB medium (Doi et al, 1988). Liquid cultivation were carried out with shaking at 30 OC for A. eutrophus and 37 oC for E. coli.…”

Section: Methodsmentioning

confidence: 99%

High frequency transformation of Alcaligenes eutrophus producing poly-?-hydroxybutyric acid by electroporation

et al. 1995

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A strain of Alcaligenes eutrophus producing poly-p-hydroxybutyric acid was successfdly transformed by the electroporation. The plasmid used was a broad host range plasmid pKT230 conferring kanamycin resistance. The optimum yield of transformant was 0.8~10~ /pg DNA when 50 ul competent cells at 10'"/ml were pulsed by 11.5 kV/cm for 5 ms with 1 pg DNA. Plasmid DNA in the A. eutrophus transformant was stably maintained as a monomeric structure.

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Nuclear magnetic resonance studies on bacterial copolyesters of 3‐hydroxybutyric acid and 3‐hydroxyvaleric acid

Cited by 33 publications

References 11 publications

SEC-MALS Characterization of Microbial Polyhydroxyalkanoates

SEC-MALS Characterization of Microbial Polyhydroxyalkanoates

Conformational analysis of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) in solution by proton NMR spectroscopy

High frequency transformation of Alcaligenes eutrophus producing poly-?-hydroxybutyric acid by electroporation

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