Abstract：
Nanostructures formed by the self-assembly of modified/unmodified amino acids have the potential to be useful in several biological/nonbiological applications. In that regard, the greater conformational space provided by γ-amino acids, owing to their additional backbone torsional degrees of freedom and enhanced proteolytic stability, compared to their α-counterparts, should be explored. Though, modified single amino acid-based nanomaterials such as nanobelts or hydrogels are developed by utilizing the monosubstituted γ-amino acids derived from the backbone homologation of phenylalanine (Phe). Examples of a single γ-amino acid-based porous nanostructure capable of accommodating solvent molecules are not really known. The crystal structures of a modified γ4(R)Phe residue, Boc-γ4(R)Phe-OH, at different temperatures, showed that hydrogen-bonded water molecules are forming a wire inside hydrophilic nanochannels. The dynamics of intermolecular interactions between the water wire and the inner wall of the channel with relation to the temperature change was investigated by analyzing the natural bonding orbital (NBO) calculation results performed with the single crystal structures obtained at different temperature points. The NBO results showed that from 325 K onward, the strength of water-water interactions in the water wire are getting weaker, whereas, for the water-inner wall interactions, it getting stronger, suggesting a favorable change in the orientation of water molecules with temperatures, for the latter.
摘要：
通过修饰/未修饰的氨基酸的自组装形成的纳米结构具有在几种生物/非生物应用中有用的潜力。在这方面,γ-氨基酸提供的构象空间越大，由于它们额外的骨架扭转自由度和增强的蛋白水解稳定性，与他们的α-同行相比，应该探索。不过,通过利用源自苯丙氨酸（Phe）的主链同源的单取代γ-氨基酸，开发了修饰的基于单氨基酸的纳米材料，例如纳米带或水凝胶。能够容纳溶剂分子的单个基于γ-氨基酸的多孔纳米结构的实例并不真正已知。修饰的γ4（R）Phe残基的晶体结构，Boc-γ4(R)Phe-OH,在不同的温度下，表明氢键结合的水分子在亲水纳米通道内形成导线。通过分析在不同温度点获得的单晶结构进行的自然键合轨道（NBO）计算结果，研究了水丝与通道内壁之间的分子间相互作用与温度变化的关系。NBO结果显示，从325K开始，水线中的水-水相互作用的强度越来越弱，然而,对于水-内壁的相互作用，它变得更强，表明水分子的取向随温度发生了有利的变化，对于后者。
