Zhao Xin, Jia Mu-Xin, Jiang Xi-Kui, Wu Li-Zhu, Li Zhan-Ting, Chen Guang-Ju
Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, China.
J Org Chem. 2004 Jan 23;69(2):270-9. doi: 10.1021/jo035149i.
Donor-acceptor interaction between electron-rich 1,5-dioxynaphthalene (DAN) and electron-deficient pyromellitic diimide (PDI) has been utilized to induce the formation of a new kind of zipper-featured delta-peptide foldamers. Seven l-ornithine-based delta-peptides 1a-g, in which one to three DNA and PDI units are incorporated to the two ends of the peptide backbones, respectively, have been designed and prepared by the standard liquid-phase synthetic method. (1)H NMR, UV-vis, and fluorescent quenching studies reveal that all the delta-peptides adopt folding conformations in nonpolar chloroform and polar DMF as a result of intramolecular donor-acceptor interaction between the DAN and PDI units. The folding states become more compact for the peptide skeletons possessing more donor-acceptor interacting sites. Variable-temperature UV-vis experiments indicate that, although the folding is a dynamic process, the folding state can remain even at 150 degrees C in DMF. Circular dichroism (CD) investigations reveal that the new generation of delta-peptides have similar folding patterns. A zipper-featured folding motif has been proposed for the new generation of delta-peptide foldamers. Molecular modeling has generated two most stable folding states for the longest delta-peptide 1g, with an energy difference of 26.80 kcal/mol.
富电子的1,5-二氧萘（DAN）与缺电子的均苯四甲酸二酰亚胺（PDI）之间的供体-受体相互作用已被用于诱导形成一种新型的具有拉链特征的δ-肽折叠体。通过标准液相合成方法设计并制备了七种基于L-鸟氨酸的δ-肽1a-g，其中一到三个DAN和PDI单元分别连接到肽主链的两端。核磁共振氢谱（¹H NMR）、紫外可见光谱和荧光猝灭研究表明，由于DAN和PDI单元之间的分子内供体-受体相互作用，所有δ-肽在非极性氯仿和极性N,N-二甲基甲酰胺（DMF）中均采用折叠构象。对于具有更多供体-受体相互作用位点的肽骨架，折叠状态变得更加紧凑。变温紫外可见光谱实验表明，尽管折叠是一个动态过程，但在DMF中即使在150℃时折叠状态仍能保持。圆二色光谱（CD）研究表明，新一代δ-肽具有相似的折叠模式。已为新一代δ-肽折叠体提出了一种具有拉链特征的折叠基序。分子模拟为最长的δ-肽1g生成了两种最稳定的折叠状态，能量差为26.80千卡/摩尔。
