Holladay L A
Biophys Chem. 1977 Jun;7(1):41-9. doi: 10.1016/0301-4622(77)87013-0.
Circular dichroic spectra obtained for S-carboxymethylated insulin A chain in water: trifluoroethanol mixtures show that a marked conformational transition occurs as the concentration of trifluoroethanol is increased to (v/v) 83% to give a polypeptide containing about 43% of the residues in the alph-helical conformation. Several proposed methods of analysis, including both linear and two nonlinear lest squares methods, were unable to quantitate the amount of beta-structure present in the polypeptide in 83% trifluoroethanol. Examination of the methods of analysis lead to the conclusion that the current models for far UV CD analysis are not adequare for the data obtained in this study and shows that nonlinear least squares procedures may lead to erroneous conclusions.
在水与三氟乙醇混合物中获得的S-羧甲基化胰岛素A链的圆二色光谱表明，随着三氟乙醇浓度增加至（v/v）83%，会发生显著的构象转变，从而形成一种α-螺旋构象中约含43%残基的多肽。包括线性和两种非线性最小二乘法在内的几种提议的分析方法，均无法对83%三氟乙醇中该多肽的β-结构含量进行定量。对分析方法的研究得出结论，当前用于远紫外圆二色分析的模型并不适用于本研究获得的数据，且表明非线性最小二乘法可能会导致错误结论。
