Small-angle X-ray scattering study on conformation of poly(sodium l-glutamate) in NaCl and NaF aqueous solutions
Small-angle X-ray scattering study on conformation of poly(sodium l-glutamate) in NaCl and NaF aqueous solutions
复制标题
聚L-谷氨酸钠在NaCl和NaF水溶液中构象的小角X射线散射研究
DOI：
10.1107/s0021889807006255
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发表时间：
2007
影响因子：
6.1
通讯作者：
K. Kurita
中科院分区：
文献类型：
--
作者：
S. Shimizu;Y. Muroga;Tatsuya Hyono;K. Kurita
采用电位滴定、高分辨率质子核磁共振 (NMR)、圆二色性 (CD) 和小角 X 射线散射 (SAXS) 技术研究了阴离子 F− 和 Cl− 对添加盐水溶液中聚谷氨酸钠 (PNaGA) 构象的影响。在 NaCl 水溶液中 PNaGA 的滴定曲线中，可以清楚地观察到四个构象区域，即聚集、螺旋、螺旋到卷曲转变和随机卷曲，但随着 F− 浓度的增加，这些区域逐渐变得模糊。 CD和NMR谱都表明PNaGA在NaF水溶液中的局部构象是无规卷曲状态，与中和度（DN）无关。 SAXS研究表明，DN = 0.25的PNaGA在0.2 NaF水溶液中的较大尺寸构象大致模仿了持久长度约为5.9 A的蠕虫状链，但DN = 0.80时的构象与孤立的蠕虫状链相去甚远。
The effect of anions F− and Cl− on the conformation of poly(sodium l-glutamate) (PNaGA) in added-salt aqueous solution was studied using potentiometric titration, high-resolution proton nuclear magnetic resonance (NMR), circular dichroism (CD) and small-angle X-ray scattering (SAXS) techniques. In the titration curve for PNaGA in NaCl aqueous solution, four conformation regions, i.e. aggregation-, helical-, helix-to-coil transition- and random-coiled, were clearly observed but these regions were gradually obscured when the concentration of F− was increased. Both CD and NMR spectra have clarified that the local conformation of PNaGA in NaF aqueous solution is a random-coiled state, independent of the degree of neutralization (DN). SAXS studies show that the conformation of a larger dimension for PNaGA having DN = 0.25 in 0.2 NaF aqueous solution is roughly mimicked by a worm-like chain having persistence length of ca 5.9 A, but the conformation at DN = 0.80 is far from an isolated worm-like chain.