Abstract
From Poria cocos mycelia yielded via a pilot scale facility–fermentation tank, a water‐insoluble (1→3)‐α‐D‐glucan coded as Pi‐PCM3‐I was isolated by extraction with 0.5 M NaOH/0.01 M NaBH~4~ aqueous solution. Nine fractions from F1 to F9 with a weight‐average molecular mass (M~w~) range from 7.75 × 10^4^ to 57.3 × 10^4^ were prepared from the Pi‐PCM3‐I sample by a nonsolvent addition method. The fractions were reacted with chlorosulfonic acid–pyridine complex to product water‐soluble sulfated derivatives coded as S1 to S8 with M~w~ from 2.36 × 10^4^ to 14.5 × 10^4^ and degree of substitution (DS) of 0.86–1.38. M~w~, z‐average radius of gyration (〈s^2^〉 ), the second virial coefficient (A~2~), and the intrinsic viscosity ([η]) of the native and sulfated Pi‐PCM3‐I were measured by laser light scattering (LLS), size‐exclusion chromatography combined with LLS (SEC–LLS), and viscometry at 25°C. The Mark–Houwink equations for Pi‐PCM3‐I in 0.25 M LiCl/dimethylsulfoxide (DMSO) (Me~2~SO) and for its sulfated derivative in 0.15 M NaCl aqueous solution at 25°C were established to be [η] = 1.33 × 10^−2^ M (mL g^–1^) and [η] = 1.46 × 10^−4^ M (mL g^–1^), respectively. On the basis of theories for a wormlike cylinder model, the conformational parameters of the native and sulfated Pi‐PCM3‐I were calculated to be 760 ± 50 and 1060 ± 30 nm^–1^ for the molar mass per unit contour length (M~L~), 6.3 ± 0.5 and 13.1 ± 1 nm for the persistence length (q), and 14.9 ± 0.2 and 31.8 ± 1 for the characteristic ratio (C~∝~), respectively. The results revealed that Pi‐PCM3‐I existed as an extended flexible chain in 0.25 M LiCl/Me~2~SO, and its sulfated derivative existed as a semistiff chain in 0.15 M NaCl aqueous solution. Furthermore, Pi‐PCM3‐I possessed similar structure and molecular parameters to wc‐PCM3‐I from a rotary shaker; this suggests promising industrialization of Poria cocos polysaccharides. © 2005 Wiley Periodicals, Inc. Biopolymers 79: 28–38, 2005
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