螺旋是生物大分子表现出的关键构象,在基本生物过程中起着关键作用。生物螺旋聚合物以单一的螺旋意义存在,这源于其主要单元的手性效应-例如,DNA和蛋白质主要采用右旋螺旋构象,以响应D-糖和L-氨基酸的不对称构象倾向,分别。在使用这些同权系统时,自然阻碍了我们对螺旋系统中协同性的一些迷人方面的观察,虽然当用于特定目的时,\"错误\"对映体可掺入特定位置。在合成螺旋系统中,相反,非外消旋手性的掺入是额外的负担,本综述中讨论的结果表明,通过利用手性放大,可以大大减轻这种负担,小的手性影响会导致大的后果。肽核酸(PNA),这是非手性合成DNA模拟物,显示了对手性氨基酸诱导的小手性效应的协同反应,这是有限的,然而,由于这种寡聚嵌合体的高度柔性。缺乏内部立体化学偏向是使PNA成为理解某些不能直接从DNA获得的合作特征的理想系统的重要因素。
The helix is a critical conformation exhibited by biological macromolecules and plays a key role in fundamental biological processes. Biological helical polymers exist in a single helical sense arising from the chiral effect of their primary units-for example, DNA and proteins adopt predominantly a right-handed helix conformation in response to the asymmetric conformational propensity of D-sugars and L-amino acids, respectively. In using these homochiral systems, nature blocks our observations of some fascinating aspects of the cooperativity in helical systems, although when useful for a specific purpose, \"wrong\" enantiomers may be incorporated in specific places. In synthetic helical systems, on the contrary, incorporation of non-racemic chirality is an additional burden, and the findings discussed in this review show that this burden may be considerably alleviated by taking advantage of the amplification of chirality, in which small chiral influences lead to large consequences. Peptide nucleic acid (PNA), which is a non-chiral synthetic DNA mimic, shows a cooperative response to a small chiral effect induced by a chiral amino acid, which is limited, however, due to the highly flexible nature of this oligomeric chimera. The lack of internal stereochemical bias is an important factor which makes PNA an ideal system to understand some cooperative features that are not directly accessible from DNA.