Study on Polysaccharide by the Fluorescence Method. II. Micro-Brownian Motion and Conformational Change of Amylose in Aqueous Solution
Study on Polysaccharide by the Fluorescence Method. II. Micro-Brownian Motion and Conformational Change of Amylose in Aqueous Solution
复制标题
荧光法研究多糖。
DOI：
10.1295/polymj.14.93
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发表时间：
1982
期刊：
影响因子：
2.8
通讯作者：
T. Kuge
中科院分区：
文献类型：
--
作者：
S. Kitamura;H. Yunokawa;S. Mitsuie;T. Kuge
采用荧光偏振法研究了直链淀粉在水溶液中的链段运动以及随温度和pH的构象转变。我们制备了两种类型的直链淀粉荧光缀合物：在整个链上随机缀合有荧光素的直链淀粉（F-直链淀粉）和在末端片段上局部缀合的直链淀粉（t-F-直链淀粉）。 t-F-直链淀粉的旋转弛豫时间值远小于F-直链淀粉。这一结果表明，末端片段比内部片段经历更快速的微布朗运动。当温度升高时，这些缀合物的偏振曲线逐渐偏离Perrin方程。 F-直链淀粉在 45°C 以上显示出逐渐偏离，但 t-F-直链淀粉在室温下显示出偏离。这表明构象转变首先发生在末端片段，然后随着温度的升高延伸到内部片段。还检查了 pH 对极化的影响。当测量 pH 值的函数时，荧光去偏振在碱性区域显着增加。与温度变化相反，两种直链淀粉缀合物在相同 pH 值下去极化开始增加。
The segmental motion of amylose in aqueous solution and the conformational transition with temperature and pH were studied by the fluorescence polarization method. We prepared two types of fluorescent conjugates of amylose: amylose conjugated with fluorescein randomly throughout chain (F-Amylose) and amylose conjugated locally on a terminal segment (t-F-Amylose). The value of the rotational relaxation time for t-F-Amylose was much smaller than that for F-Amylose. This result suggests that a terminal segment undergoes a more rapid micro-Brownian motion than interior segments. Polarization curves of these conjugates gradually departed from the Perrin equation when the temperature was raised. F-Amylose showed a gradual departure above 45°C but t-F-Amylose showed a departure at room temperature. This indicates that the conformational transition occurs first in terminal segments and then extends to the interior segments with increasing temperature. The effect of pH on the polarization was also examined. When measured as a function of pH, fluorescence depolarization increased pronouncedly in the alkaline region. In contrast to changing temperature, depolarization began to increase at the same pH for the two amylose conjugates.