黑木耳酸性杂多糖溶液性质研究

Studies on Solution Properties of Acidic Heteropolysaccharide of Auricularia Auricula-Judae

从黑木耳子实体提取出的酸性杂多糖,通过重沉淀分成8个级分,用小角激光光散射和膜渗透压法测得试样在0.5mol/L NaCl/10％镉乙二胺饱和液(C)中的M_w(5.88×10~5)、M_n(1.43×10~5)和A_2值.研究了各个分级试样在3种水溶液中30℃的粘度行为,确立了Mark-Houwink方程为:(A)0.5mol/L NaCl,[η]=0.235 M_w^(0.48);(B)0.2mol Na_2SO_4/0.01 mol/L 磷酸盐缓冲液,[η]=7.61×10^(-2)M_w^(0.57);(C)[η]=6.44×10^(-2) M_w^(0.59).无扰尺寸(S^2)_0/M及K_8为12.9×10^(-18)cm^2·mol/g及0.175cm^3/g.确证该多糖分子在溶液中呈稍刚硬的柔性无规线团状态.

A acidic heteropolysaccharide (F Ⅱ ), which is composed of D-mannose, D-xylose, D-glucose and glucuronic acid, was isolated from the fruiting body of Auricularia auricula-judae, and separated into 8 fractions by reprecipitation. The weight average molecular weights Mw, number average molecular weights Mn and second viriai coefficients A2 of fractions and unfrac-tioned samples in 0. 5 mol/L NaCl/10%cadoxen (C) were measured by low angle laser light scattering and membrane osmometry. The values of Mw and Mn of the acidic heteropolysaccharide were obtained to be: 5. 88×105 and 1. 43 ×105. Intrinsic viscosities [η] were investigated on fractioned samples in aqueous 0. 5 mol/L NaCl (A), 0. 2 mol/L Na2SO4/0. 01 mol/L phosphate buffer (B) and (C) at 30℃. The Mark-Houwink equations were established as [η] = 0. 235 Mw0.48 (A), [η] = 7. 61×10-2Mw0.57 (B) and [η] = 6. 44×10-2Mw0.59 (C). The unperturbed dimensions〈S2〉 and Kθ are respectively 12. 1 ×10-18 cm2mol g-1 and 0. 175 cm3g-1. We conclude that the acidic heteropolysaccharide behaves as a slightly stiffened random coil chain in aqueous solution.