胃泌素有关肽溶液构象的2D-NMR研究

The Study of Conformations in Solution for Gastrin with 2D NMR

用2D NMR深入研究了五肽、四肽胃泌素在DMSO中的构象。利用COSY谱、Relayed-COSY谱、DQF-J分解谱和NOESY谱归属了全部共振峰。计算了肽键平面的Φ角、旋转异构体分布和旋转异构体之间自由能差。根据NOESY谱得到了距离约束条件,结合Φ角及旋转异构体分布,推导出五肽胃泌素分子的构象模型。结果表明,五肽、四肽胃泌素在DMSO中以半角构象存在,在其主要的旋转异构体中Trp的吲哚环和Met的S原子具有类似5,1-benzothiazocine三维结构,可能是具有生物活性的原因。

The present study uses 2D NMR to evaluate the conformations in DMSO solution for Boe-pentapeptide and Boo-tetrapeptide. 2D COSY, Relayed-COSY, DQF-J Resolved Spectroscopy and NOESY were applied to assign all resonance ltnes completely, dihedral angles, rotamer populations and their energy differences were caloulated. According to NOE, conditions of distance constraints were obtained. Taken together with Φ, rotamer populations, the model of eonformaton for Boo-pentapeptide was obtained. It is shown that eonformations of Boe-pentapeptide and Boc-tetrapeptide are characterized by half turn in DMSO solution. In their main rotamers, indole of Trp and S atom of Met form a three-dimensional structure similar to 5, 1-benzothiazoine, and this strueture may be the cause of biological potency.