A novel intramolecular hydrogen bonding between a side-chain pyridine ring and an amide hydrogen of the peptide backbone in tripeptides containing the new amino acid, α,α-di(2-pyridyl)glycine
作者:Takashi Yamada、Tomoyuki Ichino、Masayuki Hanyu、Daisuke Ninomiya、Ryoji Yanagihara、Toshifumi Miyazawa、Takashi Murashima
DOI:10.1039/b406545j
日期:——
Four tripeptides (Z-AA1-2Dpy-AA3-OMe; AA1, AA3
= Gly, Aib) containing a novel amino acid, α,α-di(2-pyridyl)glycine (2Dpy), were synthesized by the modified Ugi reaction. NMR analysis clearly indicated that the 2Dpy-containing tripeptides except the peptide in which AA1, AA3
= Aib, adopt a unique conformation with two intramolecular hydrogen bonds between 2Dpy-NH and a pyridine nitrogen and between AA3-NH and another pyridine nitrogen. This conformation has so far not been reported. On the other hand, the peptide Z-Aib-2Dpy-Aib-OMe probably adopts a β-turn structure which is stabilized by two intramolecular hydrogen bonds between 2Dpy-NH and a pyridine nitrogen and between AA3-NH and the CO of the Z group.
通过改进的 Ugi 反应合成了四种含有新型氨基酸α,α-二(2-吡啶基)甘氨酸(2Dpy)的三肽(Z-AA1-2Dpy-AA3-OMe;AA1, AA3 = Gly, Aib)。核磁共振分析清楚地表明,除 AA1、AA3 = Aib 的肽外,含 2Dpy 的三肽采用了一种独特的构象,在 2Dpy-NH 与一个吡啶氮之间以及 AA3-NH 与另一个吡啶氮之间有两个分子内氢键。这种构象迄今尚未见报道。另一方面,肽 Z-Aib-2Dpy-Aib-OMe 很可能采用δ-匝结构,该结构通过 2Dpy-NH 与一个吡啶氮之间以及 AA3-NH 与 Z 基团的 CO 之间的两个分子内氢键来稳定。