生物合成聚γ-谷氨酸的相对分子质量表征

Molecular weight characteristics of poly(γ-glutamic acid)

为了确定特定条件下聚γ 谷氨酸(γ PGA)水溶液的Mark Houwink方程参数,在参数适用范围内通过特性粘度测量,对γ PGA的相对分子质量进行快捷、可靠的估计,在对钠盐型γ PGA稀溶液的粘度特性和流变性质进行了系统考察的基础上,采用凝胶渗透色谱-激光光散射联机试验(GPC LLS)和粘度方法,研究了钠盐型γ PGA的特性粘数、分子尺寸对重均相对分子质量的依赖性;建立了γ PGA在1.20mol LNaCl水溶液中的Mark Houwink方程。提出了相对分子质量的测定方法,并对均方末端距进行了估算。较大的α值表明:γ PGA大分子即使在1.20mol L的离子强度下由于聚离子的静电相斥作用仍然在溶剂中呈现出较伸展的构象,即呈棒状结构。

The dependence of intrinsic viscosity and structural parameters of bioorigin poly(γ-glutamic acid) on the weight-average molecular weight was investigated by GPC-LLS method combined with viscometric measurements for the convenient and reliable estimation of its molecular weight, founding on our former systematical research on its viscometric and rheological properties of dilute solution. The Mark-Houwink equation of poly(γ-glutamic acid)in 1.20()mol/L NaCl aqueous solution at 30()℃ was estimated as follows:The larger α value (=1.49)implies that γ-PGA macromolecular chains possess rod-like conformation resulting from the electrostatic repulsion of polyeletrolyte even in the 1.20()mol/L ionic strength.