粘度法测定水溶液中裂褶多糖分子量

Determinaion of the Relative Molecular Weight of Schizophyllan in Aqueous Solution by Viscosimeter

通过对Takashi试验数据的分析和计算,完善了粘度法测定裂褶多糖(SPG)分子量的Mark-Hou-wink公式,即在25℃的SPG水溶液中,当[η]≤445 cm-3/g时,[η]=5.19×10-7M1w.59。根据Ah-Hyun用扫描电镜(SEM)和原子力显微镜(AFM)获得SPG结构的最新数据,结合Yamakawa推导的[η]-M模型对公式进行分析。通过模型计算、粘度公式计算和凝胶过滤色谱(GPC)获得的SPG的重均分子量(Mw)分别为3.7×105、5.8×105、2.5×107,其中采用理论模型和粘度公式计算的结果较一致,而GPC测试的结果相差较大的原因可能与样品和标准分子量范围不同有关。IR和13C-NMR的数据表明该多糖具有-β(1-6)葡萄糖苷分支的-β(1-3)-D葡聚糖结构。

Mark-Houwink formula for the determination of the average molecular weight （w） of schizophyllan was supplemented on the data from Takashi＇paper. It is that [η] = 5.19 × 10^-7Mw^1.59^- when [η] ≤445 cm^-3/g. It is analysed according to the straight cylindrical macromolecules model in dilute solution by Yamakawa combined with the latest data by SEM and AFM reported by Ah-Hyun. By using Yamakawa＇model,viscosity and GPC method the molecular weight of schizophyllan purified from the fermentation suspensions was determined and the M M^- of SPG is 3.7 × 10^5 , 5.8 × 10^5 and 2.5 × 10^7 respectively. The result from viscosity is in accordance with Yamakawa＇model, while the result from GPC method is markedly different. The potential reason is the different molecular weight range between SPG and the Dextran standards. IR and ^13C-NMR data showed the purified polysaccharide consists of 1,3-βD glucopyranose units with 1,6-βD glucopyranose linkages.