Physicochemical studies on xylinan (acetan). III. Hydrodynamic characterization by analytical ultracentrifugation and dynamic light scattering
Physicochemical studies on xylinan (acetan). III. Hydrodynamic characterization by analytical ultracentrifugation and dynamic light scattering
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木聚糖（乙酰）的物理化学研究。
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发表时间：
1998
期刊：
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通讯作者：
B. Christensen
中科院分区：
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作者：
S. Harding;G. Berth;J. Hartmann;K. Jumel;H. Cölfen;B. Christensen
通过在氯化钠水溶液 (I = 0.10 mol·L−1) 中结合流体动力学测量（沉降速度和平衡分析超速离心、粘度测定和动态光散射），对实验室制备的多糖木聚糖（乙酰）样品的 (i) 纯度、(ii) 摩尔质量和多分散性以及 (iii) 总体构象进行了进一步表征。使用 Schlieren 光学记录的沉降速度图显示，高纯材料沉降为单一边界 [so20.w = 9.5 ± 0.7) S； ks=(273±112)mL/g]。这些边界的超尖锐性质是多分散和高度非理想（在热力学意义上）系统的症状。使用瑞利干涉光学和两种不同类型的外推程序（涉及点和全细胞摩尔质量）在分析超速离心机中实现低速沉降平衡，得出重均摩尔质量 Mw 为 (2.5 ± 0.5) × 10−6 g·mol−1 以及第二维里系数 B = (2.8 ± 0.7) × 10−4 mL·mol·g−2，这两个值与来自的值非常一致基于光散射的程序（本系列的第二部分）。动态光散射测量的动态 Zimm 图给出了 z 平均平移扩散系数 Do20.w = (3.02 ± 0.05) × 10−8 cm2·s−1 和浓度依赖性参数 kD = (370 ± 15) mL/g。通过 Svedberg 方程将 so20.w 与 Do20.w 组合，得出 Mw 的另一个估计值，为 ≅ 2.4 × 106 g/mol，同样吻合良好。威尔士-范霍尔德比率 (ks/[η]) ≅ 0.4（其中 [η] = (760 ± 77) mL/g）和 ρ 参数（静态光散射的回转半径与动态光散射的流体动力学半径之比）ρ > 2.0 都表明溶液中大分子的扩展构象。这些发现，加上沉降平衡数据的 Rinde 型模拟，都与之前执行的单峰蠕虫状线圈模型的解释一致。 © 1996 约翰威利父子公司。
A laboratory-made sample of the polysaccharide xylinan (acetan) has been further characterized with respect to (i) purity, (ii) molar mass and polydispersity, and (iii) gross conformation by a combination of hydrodynamic measurements (sedimentation velocity and equilibrium analytical ultracentrifugation, viscometry, and dynamic light scattering) in aqueous NaCl (I = 0.10 mol·L−1). Sedimentation velocity diagrams recorded using Schlieren optics revealed highly pure material sedimenting as a single boundary [so20.w = 9.5 ± 0.7) S; ks = (273 ± 112) mL/g]. The hypersharp nature of these boundaries is symptomatic of a polydisperse and highly nonideal (in the thermodynamic sense) system. Low speed sedimentation equilibrium in the analytical ultracentrifuge using Rayleigh interference optics and two different types of extrapolation procedure (involving point and whole-cell molar masses) gave a weight average molar mass Mw of (2.5 ± 0.5) × 10−6 g·mol−1 and also a second virial coefficient, B = (2.8 ± 0.7) × 10−4 mL·mol·g−2, both values in good agreement with those from light scattering-based procedures (Part II of this series). A dynamic Zimm plot from dynamic light scattering measurements gave a z-average translational diffusion coefficient Do20.w = (3.02 ± 0.05) × 10−8 cm2·s−1 and the concentration-dependence parameter kD = (370 ± 15) mL/g. Combination of so20.w with Do20.w via the Svedberg equation gave another estimate for Mw of ≅ 2.4 × 106 g/mol, again in good agreement. Both the Wales-van Holde ratio (ks/[η]) ≅ 0.4 (with [η] = (760 ± 77) mL/g) and the ρ-parameter (ratio of the radius of gyration from static light scattering to the hydrodynamic radius from dynamic light scattering) as ρ > 2.0 all indicate an extended conformation for the macromolecules in solution. These findings, plus Rinde-type simulations of the sedimentation equilibrium data are all consistent with the interpretation in terms of a unimodal wormlike coil model performed earlier. © 1996 John Wiley & Sons, Inc.