Precise Conformational Analysis of Some Polypeptides in the solution and liquid crystalline states by multi-nuclear NMR

我们已经证明固态^<13>C和^<15>N核磁共振化学位移值成为分析多肽在固态、溶液态和液晶态构象的基础数据。利用基础数据，利用变温高分辨率核磁共振波谱技术，阐明了长烷基侧链多肽的热致液晶形成和不形成的原因。此外，根据固态^<13>C和^<15>N NMR化学位移值，确定了溶液中蛋白质的高阶结构。氢键在形成多肽和蛋白质的稳定构象中起着重要作用。为了研究对固态多肽中羰基碳的^<13>C核磁共振位移的影响，对一系列含有甘氨酸残基的寡肽进行了^<13>C CP/ MAS核磁共振光谱测量，并通过x射线衍射确定了其晶体结构。我们发现酰胺型氢键形式的羰基碳的^<13>C化学位移随着氢键长度的减小而向下移动。这一实验发现对了解氢键的性质是很有帮助的。离子团等生物相关化合物的构象与生化功能之间的关系已通过^<13>C-NMR谱成功研究。

We have demonstrated that solid state ^<13>C and ^<15>N NMR chemical shift values become fundamental data for analyzing conformation of polypeptides in the solid state, solution state and liquid crystalline state. Using the fundamental data, the origin of the formation and no formation of thermotropic liquid crystals for polypeptides with long akyl side chains has been clarified using variable temperature high resolution NMR spectroscopy. Further, higher-order structure of proteins in solution has been determined on the basis of solid state ^<13>C and ^<15>N NMR chemical shift values.The hydrogen bond plays an important role in forming the stable conformation of polypeptides and proteins. In order to investigate the effect of on the ^<13>C NMR chemical shifts of carbonyl carbons in peptides in the solid state, ^<13>C CP/ MAS NMR spectra were measured for a series of the oligopeptides containing glycine residues of which the crystal structures were already determined by X-ray diffraction We have found that the ^<13>C chemical shifts of the carbonyl carbon in the amide type hydrogen bond form move downfield with a decrease in the hydrogen bond length. This experimental finding is very useful to know the nature of hydrogen bond.The relationship between the conformation and the biochemical function in biologically-related compounds such as ionophores has been successfully studied by ^<13>C-NMR spectroscopy.