The interaction of carboxymethylamylose and diethylaminoethylamylose with iodine
The interaction of carboxymethylamylose and diethylaminoethylamylose with iodine
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羧甲基直链淀粉和二乙氨基乙基直链淀粉与碘的相互作用
DOI：
10.1002/bip.1977.360160504
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发表时间：
1977
期刊：
影响因子：
2.9
通讯作者：
D. Brant
中科院分区：
文献类型：
--
作者：
A. Cesàro;D. Brant
在碘化物（I2/I−）存在的情况下，用碘对微取代的羧甲基链淀粉（CM‐Amy）和二乙胺乙基链淀粉（DEAE‐Amy）进行了分光光度滴定，作为碘化物浓度、温度和聚合物电荷的函数。聚合物- I2/I -配合物的结合等温线是根据表观结合常数（Ka）与配合物饱和度（θ）绘制的。Ka对聚合电荷的依赖被解释为结合物带负电荷的证据。结合过程的协同性质在Ka vs （θ）的正斜率中表现得很明显。虽然直链淀粉- I2/I -复合物的表观结合常数和配合度小于直链淀粉- I2/I -复合物，但根据Ka在θ = 0.5时的温度依赖性推导出的结合焓对于直链淀粉和CM - Amy来说似乎是相同的。在CM - Amy - I2/I -溶液和无聚合物溶剂相之间的透析平衡下，用I2/I -对充满电的CM - Amy进行了粘度滴定，发现在特性粘度（[η]） vs θ图中存在最大值。在小θ处[η]的增加被解释为由负电荷束缚物的吸收引起的聚电解质膨胀的反映；随后的[η]下降归因于紧凑螺旋序列的I2/I−稳定化或在较高θ处形成分子间聚集体。
Spectrophotometric titrations of slightly substituted carboxymethylamylose (CM‐Amy) and diethylaminoethylamylose (DEAE‐Amy) with iodine in the presence of iodide (I2/I−) were carried out as a function of iodide concentration, temperature, and polymeric charge. Binding isotherms for the polymer‐I2/I− complex are reported in terms of an apparent binding constant (Ka) plotted versus degree of saturation of the complex (θ). The dependence of Ka upon polymeric charge is interpreted as evidence for the negatively charged character of the bound species. The cooperative nature of the binding process is evident in the positive slope of Ka vs (θ). Whereas the apparent binding constants and binding cooperativities for the derivatives are smaller than for the amylose‐I2/I− complex, the binding enthalpies deduced from the temperature dependence of Ka at θ = 0.5 appear to be the same for amylose and CM‐Amy. A viscometric titration of fully charged CM‐Amy with I2/I−, conducted at dialysis equilibrium between the CM‐Amy‐I2/I− solution and the polymer‐free solvent phase, disclosed a maximum in the plot of intrinsic viscosity ([η]) vs θ. The increase in [η] at small θ was interpreted as a reflection of polyelectrolyte expansion provoked by absorption of the negatively charged bound species; the subsequent decline in [η] is attributed to stabilization by I2/I− of compact helical sequences or to the formation at higher θ of intermolecular aggregates.