裂褶菌胞外多糖的粘度性质及其构象研究

采用高效凝胶渗透色谱(GPC)测定了裂褶菌胞外多糖(SPG)的分子量；借助乌氏粘度计和旋转粘度计研究了温度、pH、变性剂(脲)和金属离子(Na~+、K~+、Mg~(2+)、Ca~(2+))对裂褶多糖溶液粘度的影响；采用刚果红染色法分析了NaOH和盐的浓度对SPG构象的影响。研究表明，所分离的裂褶多糖的重均分子量(Mw)和数均分子量(Mn)分别为2.5×10~7u和1.2×10~7u，特性粘数为625.29mL／g。质量浓度为0.010％的SPG表现为牛顿流体，大于此浓度则表现为非牛顿流体。随着温度的升高(20～70℃)，其相对粘度逐渐降低。0.1～0.3mol／LHCl和0.1mol／LNaOH的加入使其粘度有所增加，随着酸和碱浓度的增加，SPG溶液粘度逐渐降低。但加入不同浓度的HCl，其粘度均大于对照值；而浓度大于0.5mol／L的NaOH则会使其粘度降低至对照值以下。不同浓度的金属离子的加入可使SPG溶液的粘度增加，但Mg~(2+)、Ca~(2+)比Na~+、K~+对SPG粘度的影响较大。0.1～0.7mol／L脲使其粘度有所增加。刚果红实验表明，NaOH可以使SPG的三螺旋结构解体，而不同浓度的Na~+、K~+都可以稳定其构象，其中K~+更为显著。

Research on the Viscosity and Conformation Character of Schizophyllan

Viscosity and conformation character of Schizophyllan(SPG) with intrinsic viscosity of 625.29 mL/g,weight-averaged(Mw) and number-averaged(Mn) molecular weights of 2.5×10~7 and 1.2×10~7 respectively measured by Gel Permeation Chromatography(GPC) were studied with Ubbelohde-type viscometer and rotating cylinder viscometer as well as ultraviolet spectrometer. 0.010% (wt%) SPG aqueous system behaves as Newtonian fluids and its viscosity decreases with the increasing of temperature from 20℃ to 70℃. The viscosity of SPG solution increases with 0.1～0.3 mol/L hydrochloric acid or 0.1 mol/L sodium hydroxide solution, but it decreases with higher concentration of hydrochloric acid or sodium hydroxide solution. However the viscosity of SPG aqeous with above 0.5 mol/L sodium hydroxide solution is smaller than that of blank which contains distilled water of the same Volume as the sodium hydroxide, while the viscosity of SPG aqeous with 0.1～0.7 mol/L hydrochloric acid is higher than that of blank. The viscosity of SPG aqeous can be improved by all of Na~+ ,K~+ ,Mg~(2+) ,Ca~(2+) and is obviously increased even more by Mg~(2+), Ca~(2+) than Na~+, K~+. The congo red colouration experiment showed that the triple helix structure of SPG can be destroyed by sodium hydroxide solution and the ordered structure can be stablized by certain concentrations of Na~+ and K~+, especially by K~+ in the experiment.