CAS Key Laboratory of Biological Effects of Nanomaterials and Nanosafety, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience , National Center for Nanoscience and Technology , Beijing 100190 , P. R. China.
Department of Chemistry , Tsinghua University , Beijing 100084 , P. R. China.
Nano Lett. 2019 Aug 14;19(8):5403-5409. doi: 10.1021/acs.nanolett.9b01904. Epub 2019 Jul 5.
Amino acid chirality has been recognized as an important driving force in constructing peptide architectures, via interactions such as chirality-induced stereochemical effect. The introduction of site-specific chiral conversion of l- and d-amino acids in peptide sequences could enable the pursuit of the chirality effects in peptide assembly. In this work, we characterized the assemblies of heptapeptides with various side chain moieties and their chiral variants using STM. Specifically, two pairs of amino acids, Gln (Q) and Asn (N), Glu (E) and Asp (D), having one methylene difference in their side chains, are selected to elucidate the steric dependence of amino acid chiral effects on surface-bound peptide assemblies. The observed heptapeptide assembly structures reveal that chirality switching of a single amino acid is able to destabilize the surface-mediated peptide assemblies, and this disturbance effect can be positively correlated with the steric hindrance of amino acid side chains. Furthermore, the strength of the impact due to chiral conversion on heptapeptide assembly structure is noticeably dependent on the mutation sites, indicative of structural heterogeneity of chiral effects. These results could contribute to the molecular insights of chirality-induced stereochemical interactions in peptide assembly.
氨基酸手性已被认为是通过手性诱导立体化学效应等相互作用构建肽结构的重要驱动力。在肽序列中引入 l-和 d-氨基酸的定点手性转换可以实现对肽组装中手性效应的研究。在这项工作中，我们使用 STM 对具有各种侧链基团的七肽及其手性变体的组装进行了表征。具体来说，选择 Gln（Q）和 Asn（N）、Glu（E）和 Asp（D）这两对氨基酸，它们的侧链仅相差一个亚甲基，以阐明氨基酸手性效应对表面结合肽组装的立体依赖性。观察到的七肽组装结构表明，单个氨基酸的手性转换能够使表面介导的肽组装失稳，这种干扰效应可以与氨基酸侧链的空间位阻呈正相关。此外，由于手性转换对七肽组装结构的影响强度明显取决于突变位点，表明手性效应的结构异质性。这些结果有助于深入了解肽组装中手性诱导的立体化学相互作用的分子机制。
