离子强度对壳聚糖分子链构象的影响 - 食品科学.pdf

34 2014, Vol.35, No.09 食品科学 ※基础研究 离子强度对壳聚糖分子链构象的影响 1 2,* 张 威 ，夏文水 （1.武汉轻工大学食品科学与工程学院，湖北 武汉  430023； 2.江南大学食品学院，食品科学与技术国家重点实验室，江苏 无锡  214 122 ） 摘  要：通过特性黏度法和光散射法研究离子强度对高（7 12.6 kD ）、中（205.8 kD ）、低（76.4 kD ）3 种分子质 量壳聚糖分子链构象的影响。结果表明：随着离子强度的增加，3 种壳聚糖的特性黏度均降低，分子链均方旋转半 径也表现出下降趋势。壳聚糖分子质量越高，分子链刚性度越低。溶液中离子强度升高时，质子化氨基逐渐被反离 子屏蔽，这可能是壳聚糖特性黏度和分子链均方旋转半径下降的原因。因此，壳聚糖的增稠效果可通过控制环境条 件改变壳聚糖的分子链构象进行调节。 关键词：壳聚糖；离子强度；链刚性度；均方旋转半径；Zeta 电位 Effect of Ionic Strength on Chain Conformation of Chitosan 1 2,* ZHANG Wei , XIA Wen-shui (1. College of Food Science and Engineering, Wuhan Polytechnic University, Wuhan 430023, China; 2. State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214 122, China) Abstract: The effect of ionic strength on the chain conformations of high (7 12.6 kD), medium (205.8 kD) and low (76.4 kD) molecular weight chitosan was studied by intrinsic viscosity and static light scattering. Our results showed that the intrinsic viscosities and mean square radiuses of the three samples decreased with increasing ionic strength. The chain stiffness of chitosan became weak as the molecular weight increased. With an increase in ionic strength, the protonated amino groups of chitosan chains were gradually screened by counter ions, which might account for the decrease in intrinsic viscosity and mean square radius of gyration. This study indicated that the thickening effect of chitosan could be regulated by changing its chain conformation through the adjustment of environment