Thunecke F, Fischer G
Max-Planck Research Unit Enzymology of Protein Folding, Halle/Saale, Germany.
Electrophoresis. 1998 Feb;19(2):288-94. doi: 10.1002/elps.1150190224.
Conformer-specific recognition of peptides and proteins has often been proved with the aid of indirect methods. Here we provide an analytical approach for a direct investigation of separated isomers. Cis/trans conformers of the peptide hormones human (hCT) and salmon (sCT) calcitonin exhibit different migration properties in capillary zone electrophoresis at subambient temperatures. Calcitonin consists of 32 amino acids with two proline residues incorporated. It is the longest unstructured peptide for which a conformer separation by capillary electrophoresis has yet been achieved. Lowering the temperature yielded a splitting into two and three peaks for sCT and hCT, respectively, in acidic buffer. The peak ratios of 66:34 for sCT and 71:23 for hCT are in good agreement with the conformer distribution previously reported from nuclear magnetic resonance (NMR) studies. The addition of different organic modifiers (5-20% v/v) to the running buffer does not improve the separation. The observed merging of conformer peaks in buffer containing 20% v/v 2,2,2-trifluoroethanol (TFE) is attributed to structure formation.
肽和蛋白质的构象异构体特异性识别通常借助间接方法得以证实。在此，我们提供一种分析方法，用于直接研究分离的异构体。人降钙素（hCT）和鲑鱼降钙素（sCT）这两种肽类激素的顺式/反式构象异构体在亚环境温度下的毛细管区带电泳中呈现出不同的迁移特性。降钙素由32个氨基酸组成，包含两个脯氨酸残基。它是迄今为止通过毛细管电泳实现构象异构体分离的最长的无结构肽。在酸性缓冲液中降低温度时，sCT和hCT分别产生两个和三个峰的分裂。sCT的峰比为66:34，hCT的峰比为71:23，这与先前核磁共振（NMR）研究报道的构象异构体分布高度吻合。向运行缓冲液中添加不同的有机改性剂（5 - 20% v/v）并不能改善分离效果。在含有20% v/v 2,2,2 - 三氟乙醇（TFE）的缓冲液中观察到的构象异构体峰的合并归因于结构形成。
