A water-insoluble (1→3)-α-D-glucan (ab-PCM3-I) isolated from the Poria cocos mycelia by extracting with 0.5 sodium hydroxide was fractionated into ten fractions by non-solvent addition method in 0.25 M lithium chloride in dimethylsulfoxide. Seven fractions were treated with chlorosulfonic acid-pyridine complex to synthesis water-soluble sulfated derivatives (S-ab-PCM3-I) with degrees of substitution in the range 0.35-0.81. The solution behaviours of the α-D-glucan and its derivatives were studied by laser light scattering (LLS), size exclusion chromatography combined with laser light scattering (SEC-LLS) and viscometry at 25 °C. The dependences of intrinsic viscosity ([η]) on weight-average molecular mass (Mw) for the native glucan and the sulfated derivatives were found to be [η]=9.92*10^−3 Mw0.77 (cm3 g−1) in the range of Mw from 1.08 to 23.1*10^4 and [η]=2.92*10^−4 Mw1.09 (cm3 g−1) in the range of Mw from 0.74 to 5.80*10^4, respectively. On the basis of current theories for a wormlike chain model, the conformation parameters of the samples ab-PCM3-I and S-ab-PCM3-I were calculated to be 584 and 834 nm−1 for the molar mass per unit contour length (ML), 3.7 and 6.8 nm for the persistence length (q), 11.6 and 18.1 for characteristic ratio (C∞), respectively. The results indicated that the α-D-glucan ab-PCM3-I exists as an extended random coil chain in 0.25 M lithium chloride in dimethylsulfoxide, and that the sulfated derivatives S-ab-PCM3-I has good water-solubility and exist as semi-stiff chains in 0.9% w/v aqueous sodium chloride, owing to the steric hindrance and electrostatic repulsion of the sulfate groups.
conformation, molecular mass, sulfated derivative, (1→3)-α-D-glucan, Poria cocos mycelia
Publication DOI: 10.1016/j.carbpol.2004.09.017Journal NLM ID: 8307156Publisher: Elsevier
Correspondence: Zhang L
Institutions: Department of Chemistry, Wuhan University, Wuhan, China, Department of Biology, The Chinese University of Hong Kong, Hong Kong, China, College of Chemistry and Environment Engineering, Jianghan University, Wuhan, China, Birmingham Carbohydrate and Protein Technology Group, School of Chemical Sciences, The University of Birmingham, Birmingham, UK, Chembiotech Laboratories, University of Birmingham Research Park, Vincent Drive, Birmingham, UK
Methods: conformation analysis, FTIR, light scattering, viscosity measurement, sulfation, SEC-MALLS
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