National Centre for Macromolecular Hydrodynamics, University of Nottingham, Sutton Bonington, LE12 5RD, UK.
National Centre for Macromolecular Hydrodynamics, University of Nottingham, Sutton Bonington, LE12 5RD, UK; Insulin and Diabetes Experimental Research (IDER) Group, University of Nottingham, Faculty of Medicine and Health Science, Clifton Boulevard, Nottingham, NG7 2RD, UK.
Carbohydr Polym. 2015 May 20;122:359-66. doi: 10.1016/j.carbpol.2014.09.090. Epub 2014 Oct 14.
Chitosan, a soluble polycationic derivative of insoluble chitin, has been widely considered for use in the food, cosmetic and pharmaceutical industries. Commercial ("C") and in-house laboratory ("L") prepared chitosan samples extracted from crustaceous shells with different molecular weight and degrees of acetylation (25% and 15%) were compared with regards to (i) weight-average molecular weight (Mw); (ii) sedimentation coefficient (s(o)(20,w)) distribution, and (iii) intrinsic viscosity ([η]). These parameters were estimated using a combination of analytical ultracentrifugation (AUC), size exclusion chromatography coupled to multi-angle laser light scattering (SEC-MALS) and differential pressure viscometry. Polydisperse distributions were seen from sedimentation coefficient distributions and elution profiles from SEC-MALS. Mw values obtained for each sample by sedimentation equilibrium measurements were in excellent agreement with those obtained from SEC-MALS. Mark-Houwink-Kuhn-Sakurada (MHKS) and Wales van Holde analyses of the data all suggest a semi-flexible conformation. The principle of co-sedimentation was then used to monitor the interactions of the two different molecular weights of L chitosans with two polyanions, DNA and xanthan (another double helical high molecular weight molecule). Interactions were clearly observed and then quantified from the changes in the sedimentation coefficient distribution of the mixture compared to unmixed controls using sedimentation velocity. The interactions appeared to show a strong dependence on molecular weight. The relevance of this for DNA condensation applications is indicated.
壳聚糖是不溶性几丁质的可溶性聚阳离子衍生物，已广泛用于食品、化妆品和制药行业。本文比较了商业（“C”）和内部实验室（“L”）制备的壳聚糖样品，这些壳聚糖样品是从甲壳类动物外壳中提取的，具有不同的分子量和乙酰化程度（25%和 15%），比较的方面有：（i）重均分子量（Mw）；（ii）沉降系数（s(o)(20,w)）分布，以及（iii）特性粘度([η])。使用分析超速离心（AUC）、与多角度激光光散射（SEC-MALS）相结合的尺寸排阻色谱法和差压粘度计，对这些参数进行了估算。从沉降系数分布和 SEC-MALS 的洗脱谱中可以看出多分散分布。通过沉降平衡测量获得的每个样品的 Mw 值与通过 SEC-MALS 获得的值非常吻合。MHKS 和 Wales van Holde 对数据的分析都表明，其构象为半柔性。然后，使用共沉降原理监测两种不同分子量的 L 壳聚糖与两种聚阴离子（DNA 和黄原胶（另一种双螺旋高分子量分子））之间的相互作用。从混合物与未混合对照物相比，沉降系数分布的变化，使用沉降速度清楚地观察到并定量了相互作用。相互作用似乎强烈依赖于分子量。这对 DNA 缩合应用具有重要意义。
