Abstract：
Oligourea foldamers are known to fold into 2.5-helices, stabilized by three-centered hydrogen bonds, which makes them conformationally more rigid than peptides. Nevertheless, the folding propensity and conformational stability in solution depend on the length of the oligomer, as well as the temperature, solvent, and so forth. In the peptide field, there are many approaches known for constraining the backbone in the folded conformation, including the stapling of side chains by disulfide bridges, lactam formation, ring closing metathesis reaction, and others. In this work, we linked side chains by lactam bridges of short oligoureas (four residues), containing Glu- and Lys-like residues. The designed oligoureas differed in the position of the Glu-like residue. Next, the conformational properties of linear and cyclic compounds were studied in protic solvent (methanol) by nuclear magnetic resonance and circular dichroism. Importantly, it was discovered that larger macrocycles (24-membered) are more tolerated with respect to the helical turn than smaller macrocycles (19-membered) under the studied conditions.
摘要：
众所周知，Oligourea折叠器可以折叠成2.5螺旋，由三个中心的氢键稳定，这使得它们在构象上比肽更刚性。然而，在溶液中的折叠倾向和构象稳定性取决于寡聚体的长度，以及温度，溶剂,等等。在肽领域，有许多已知的方法将骨架限制在折叠构象中，包括通过二硫键钉住侧链，内酰胺形成，闭环复分解反应，和其他人。在这项工作中,我们通过短寡聚体（四个残基）的内酰胺桥连接侧链，含有Glu和Lys样残留物。设计的寡聚体在Glu样残基的位置上有所不同。接下来,用核磁共振和圆二色性研究了线性和环状化合物在质子溶剂（甲醇）中的构象性质。重要的是,发现在所研究的条件下,较大的大环(24-元)比较小的大环(19-元)更耐受螺旋转角。
