Huang Qilin, Zhang Lina
Department of Chemistry, Wuhan University, Wuhan 430072, China.
Biopolymers. 2005 Sep;79(1):28-38. doi: 10.1002/bip.20332.
From Poria cocos mycelia yielded via a pilot scale facility-fermentation tank, a water-insoluble (1-->3)-alpha-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 x 10(4) to 57.3 x 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 x 10(4) to 14.5 x 10(4) and degree of substitution (DS) of 0.86-1.38. M(w), z-average radius of gyration (s(2) (z) (1/2)), the second virial coefficient (A(2)), and the intrinsic viscosity ([eta]) 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 degrees 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 degrees C were established to be [eta] = 1.33 x 10(-2) M(w) (0.75+/-0.01) (mL g(-1)) and [eta] = 1.46 x 10(-4) M(w) (1.13+/-0.01) (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( proportional, variant)), 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.
通过中试规模的发酵罐从茯苓菌丝体中提取出一种水不溶性的（1→3）-α-D-葡聚糖，编码为Pi-PCM3-I，用0.5 M NaOH/0.01 M NaBH₄水溶液进行提取。采用非溶剂添加法从Pi-PCM3-I样品中制备了九个级分，从F1到F9，重均分子量（M(w)）范围为7.75×10⁴至57.3×10⁴。这些级分与氯磺酸-吡啶络合物反应，生成水溶性硫酸化衍生物，编码为S1至S8，M(w)为2.36×10⁴至14.5×10⁴，取代度（DS）为0.86 - 1.38。在25℃下，通过激光光散射（LLS）、尺寸排阻色谱与LLS联用（SEC-LLS）以及粘度测定法，测量了天然和硫酸化Pi-PCM3-I的M(w)、z-平均回转半径（s₂(z)¹/₂）、第二维里系数（A₂）和特性粘度（[η]）。建立了Pi-PCM3-I在0.25 M LiCl/二甲基亚砜（DMSO）（Me₂SO）中以及其硫酸化衍生物在0.15 M NaCl水溶液中于25℃时的Mark-Houwink方程，分别为[η] = 1.33×10⁻²M(w)(0.75±0.01)(mL g⁻¹)和[η] = 1.46×10⁻⁴M(w)(1.13±0.01)(mL g⁻¹)。基于蠕虫状圆柱体模型理论，计算出天然和硫酸化Pi-PCM's-I的构象参数，单位轮廓长度的摩尔质量（M(L)）分别为760±50和1060±30 nm⁻¹，持久长度（q）分别为6.3±0.5和13.1±1 nm，特征比（C(∝,变体)）分别为14.9±0.2和31.8±1。结果表明，Pi-PCM3-I在0.25 M LiCl/Me₂SO中以伸展的柔性链形式存在，其硫酸化衍生物在0.15 M NaCl水溶液中以半刚性链形式存在。此外，Pi-PCM3-I与旋转摇床培养的wc-PCM3-I具有相似的结构和分子参数；这表明茯苓多糖具有良好的工业化前景。
