Zhang L, Yang L
Department of Chemistry, Wuhan University, China.
Biopolymers. 1995 Dec;36(6):695-700. doi: 10.1002/bip.360360603.
A water-soluble glucan A was isolated from the fruit body of Auricularia auricula-judae. It is composed of a backbone chain of beta-(1-->3)-linked D-glucose residues, two out of three glucose residues being substituted at C-6 positions with a single glucose unit. The weight average molecular weight Mw, number average molecular weight Mn, and intrinsic viscosity [eta] of the fractionated samples were studied at 25 degrees C in water and in dimethylsulfoxide (DMSO). The Mark-Houwink equation was established as [eta] = 6.10 x 10(-4) Mw1.14 for the glucan A having Mw ranging from 9 x 10(5) to 1.6 x 10(6) in water. The values of [eta] in water are far higher than those in DMSO, but the values of Mn measured in water are the same as those in DMSO. Analysis of Mw and [eta] in terms of the known theories for rods and wormlike chains yielded 1030 +/- 100 nm-1, 90 +/- 20 nm, 1.3 +/- 0.3 nm, and 0.26 +/- 0.03 nm for molar mass per unit contour length ML, persistence length q, diameter d, and contour length h per main-chain glucose residue, respectively. The present data suggest that glucan A dissolves in water as single-stranded helical chains and in DMSO as semiflexible chains.
从黑木耳子实体中分离出一种水溶性葡聚糖A。它由β-(1→3)连接的D-葡萄糖残基的主链组成，每三个葡萄糖残基中有两个在C-6位被单个葡萄糖单元取代。在25℃下于水和二甲基亚砜（DMSO）中研究了分级分离样品的重均分子量Mw、数均分子量Mn和特性粘度[η]。对于在水中Mw范围为9×10⁵至1.6×10⁶的葡聚糖A，Mark-Houwink方程确定为[η]=6.10×10⁻⁴Mw¹.¹⁴。水中的[η]值远高于DMSO中的值，但在水中测得的Mn值与DMSO中的相同。根据关于棒状和蠕虫状链的已知理论对Mw和[η]进行分析，得到每主链葡萄糖残基的单位轮廓长度摩尔质量ML为1030±100nm⁻¹、持久长度q为90±20nm、直径d为1.3±0.3nm、轮廓长度h为0.26±0.03nm。目前的数据表明，葡聚糖A在水中以单链螺旋链形式溶解，在DMSO中以半柔性链形式溶解。
