世界発！理論上は可能とされた“らせん構造”を実現～分子が自発的に作るナノチューブ構造、未来の材料開発に光～

2025-05-19 広島大学

図1．人工アミノ酸Aibペプチドが与えるらせん構造から作られる結晶

＜関連情報＞

• https://www.hiroshima-u.ac.jp/news/90375
• https://www.hiroshima-u.ac.jp/system/files/260534/An%20%CE%B1-Helically%20Folded%20%CE%B1-Aminoisobutyric%20Acid%20%28Aib%29%20Oligomer%20that%20Assembles%20into%20a%20Metal%E2%80%93Peptide%20Superhelical%20Nanotube.pdf
• https://pubs.acs.org/doi/10.1021/jacs.5c03534

α-アミノイソ酪酸(Aib)オリゴマーは金属-ペプチドスーパーヘリカルナノチューブに集合する An α-Helically Folded α-Aminoisobutyric Acid (Aib) Oligomer That Assembles into a Metal–Peptide Superhelical Nanotube

Wei Yuan,Jenny Pirillo,Yuh Hijikata,Takuzo Aida,and Hiroshi Sato
Journal of the American Chemical Society  Published May 15, 2025
DOI:https://doi.org/10.1021/jacs.5c03534

Abstract

α,α-Disubstituted α-amino acids such as α-aminoisobutyric acid (Aib), in their polymeric structures, are known to form a 3₁₀-helical conformation rather than an α-helical conformation, which is usually adopted by polymeric α-monosubstituted α-amino acids. Even α-helically folded Aib oligomers are unprecedented, although they have been predicted by theoretical calculations. In the present paper, we report the first α-helically folded Aib oligomer found in the course of our study on the construction of a metal–peptide framework, ^AibMOF-1. This MOF was synthesized by Zn²⁺-mediated complexation of a pyridyl-functionalized Aib hexamer, Py-Aib₆-Py, and 5-nitroisophthalate (nip^2–). Single crystal X-ray diffraction of ^AibMOF-1 ([Zn(nip)(Py-Aib₆-Py)]_n) revealed that Py-Aib₆-Py in ^AibMOF-1 carried a C═O_i → NH_i+4 hydrogen bonding array characteristic of α-helices, which is distinct from Py-Aib₆-Py alone adopting a 3₁₀-helical conformation with a C═O_i → NH_i+3 hydrogen bonding array. The α-helical Py-Aib₆-Py units in ^AibMOF-1 assembled into a superhelical nanotubular architecture with a porous framework. When just the nitro group of the coligand nip^2– was changed to a tert-butyl group, an MOF (^AibMOF-2) with a completely different structure formed, where the constituent Py-Aib₆-Py units adopted only the 3₁₀-helical conformation, just like Py-Aib₆-Py in its crystalline structure.