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首页> 外文期刊>Biophysical Chemistry: An International Journal Devoted to the Physical Chemistry of Biological Phenomena >The gel-forming behaviour of dextran in the presence of KCl: a quantitative 13C and pulsed field gradient (PFG) NMR study.
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The gel-forming behaviour of dextran in the presence of KCl: a quantitative 13C and pulsed field gradient (PFG) NMR study.

机译：在氯化钾存在下右旋糖酐的凝胶形成行为：定量13 C和脉冲场梯度（PFG）NMR研究。

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摘要

Although the gel forming ability of certain polysaccharides in the presence of ions is a well-known phenomenon, detailed physicochemical mechanisms of such processes are still unknown. In this investigation high resolution 13C NMR as well as 1H pulsed field gradient (PFG) NMR were used to investigate the mobility of dextran in the sol and in the gel state. Gel-formation of dextran can be easily induced by the addition of large amounts of potassium chloride. No major differences in the T(1) relaxation times of dextran in the sol and in the gel state could be observed. Accordingly, the analysis of the 13C NMR spectroscopic data did not provide any indication of an observable line-broadening upon gel-formation. However, a KCl concentration dependent decrease of signal intensity in comparison to an internal standard was detected. On the other hand, the PFG NMR studies clearly indicated a gradual diminution of the self-diffusion coefficient of the dextran with increasing molecular weight as well as in the presence of potassium chloride. These measurements revealed in agreement with spectroscopic data that at least one potassium ion per monomer subunit (i.e. one glycopyranose residue) is necessary for gel formation.
机译：尽管某些多糖在离子存在下的凝胶形成能力是众所周知的现象，但是这些过程的详细物理化学机理仍然未知。在这项研究中，高分辨率13C NMR和1H脉冲场梯度（PFG）NMR用于研究葡聚糖在溶胶和凝胶状态下的迁移率。右旋糖酐的凝胶形成很容易通过添加大量的氯化钾来诱导。在溶胶和凝胶状态下，未观察到右旋糖酐在T（1）弛豫时间上的主要差异。因此，对13 C NMR光谱数据的分析没有提供凝胶形成时可观察到的谱线扩大的任何迹象。但是，与内标相比，检测到了KCl浓度依赖性的信号强度下降。另一方面，PFG NMR研究清楚地表明，随着分子量的增加以及在氯化钾的存在下，葡聚糖的自扩散系数逐渐减小。这些测量结果与光谱数据一致，即每个凝胶中每个单体亚基至少需要一个钾离子（即一个吡喃葡萄糖残基）。

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