Solution properties of synthetic polypeptides. XVIII: Helix–coil transition of poly‐N5‐(2‐hydroxyethyl)L‐glutamine
Solution properties of synthetic polypeptides. XVIII: Helix–coil transition of poly‐N5‐(2‐hydroxyethyl)L‐glutamine
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XVIII 合成多肽的溶液特性：聚-N5-(2-羟乙基)L-谷氨酰胺的螺旋-螺旋转变。
DOI：
10.1002/bip.1974.360130609
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发表时间：
1970
期刊：
影响因子：
2.9
通讯作者：
H. Fumita
中科院分区：
文献类型：
--
作者：
M. Miyake;Shuichi Akita;A. Teŕamoto;T. Norisuye;H. Fumita
用旋光色散（ORD）和特性粘数[η]研究了聚N-5-（2-羟乙基）-L-谷氨酰胺（PHEG）在异丙醇水溶液中的螺旋-卷曲转变。从ORD数据确定了作为分子量函数的转变的Zimm-Bragg参数σ和s。结果发现，过渡的特点是一个相对较低的协同性;的值的\documentclass{article}\pagestyle{empty}\开始{document}$ \sqrt \sigma $\end{document}的范围从0.039到0.066，这取决于溶剂的组成。这些σ值远大于其它多肽-溶剂系统所报道的值。的转变焓是负的，其大小与溶剂的组合物，在40重量%异丙醇的最大值为620卡/摩尔。高分子量样品的[η]与螺旋含量的曲线显示出非常宽的最小值，这种行为归因于过渡的低协同性。
The helix–coil transition of poly‐N5‐(2‐hydroxyethyl)L‐glutamine (PHEG) in aqueous isopropanol was examined by means of optical rotatory dispersion (ORD) and intrinsic viscosity [η] measurements. The Zimm–Bragg parameters σ and s for the transition were determined from the ORD data as a function of molecular weight. It was found that the transition was characterized by a relatively low cooperativity; the values of \documentclass{article}\pagestyle{empty}\begin{document}$ \sqrt \sigma $\end{document} were in the range from 0.039 to 0.066, depending on the solvent composition. These σ values are much larger than those reported for other polypeptide–solvent systems. The transition enthalpy was negative and its magnitude varied with the solvent composition, with a maximum of 620 cal/mol at 40 wt% isopropanol. The curve of [η] versus helical content for a high‐molecular‐weight sample exhibited a very broad minimum, and this behavior was attributed to the low cooperativity of the transition.