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首页> 外文期刊>Chemistry: A European journal >Homochiral Oligopeptides by Chiral Amplification within Two-Dimensional Crystalline Self-Assemblies at the Air-Water Interface; Relevance to Biomolecular Handedness
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Homochiral Oligopeptides by Chiral Amplification within Two-Dimensional Crystalline Self-Assemblies at the Air-Water Interface; Relevance to Biomolecular Handedness

机译：通过手性扩增在空气-水界面的二维晶体自组装中的同手性寡肽;与生物分子操纵性的关系

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摘要

A possible role that might have been played by ordered clusters at interfaces for the generation of homochiral oligopeptides under prebiotic conditions has been probed by a catalyzed polymerization of amphiphilic activated alpha-amino acids, in racemic and chiral non-racemic forms, which had self-as-sembled into two-dimensional (2D) ordered crystallites at the air-aqueous solution interface. As model systems we studied N~epsilon-stearoyl-lysine thioethyl ester (C_18-TE-Lys), gamma-stearyl-glutamic thioethyl ester (C_18-TE-Glu), N~alpha-carboxyanhydride of gamma-stearyl-glutamic acid (C_18-Glu NCA) and gamma-stearyl-glutamic thioacid (C_18-thio-Glu). According to insitu grazing incidence X-ray diffraction measurements on the water surface, (R,S)-C_18-TE-Lys, (R,S)-C_18-TE-Glu, and (R,S)-C_18-Glu-NCA amphiphies self-assembled into ordered racemic 2D crystallites. Oligopeptides 2-12 units long were obtained at the air-a-queous solution interface after injection of appropriate catalysts into the water subphase. The experimental relative abundance of oligopeptides with homochiral sequence generated from (R,S)-C_18-TE-Lys and (R,S)-C_18-TE-Glu, as determined by mass spectrometry on enantioselectively deuterium-labeled samples, was found to be significantly larger than that obtained from (R,S) C_18-thio-Glu which polymerizes randomly. An efficient chiral amplification was obtained in the polymerization of non-racemic mixtures of C_18-Glu-NCA since the monomer molecules in the racemic 2D crystallites are oriented such that the reaction occurs between heterochiral molecules related by glide symmetry to yield heterochiral oligopeptides whereas the enantiomer in excess, in the enan-tiomorphous crystallites, yield oligopeptides of a single handedness.
机译：在益生元条件下，有序簇在界面上可能产生同型手性寡肽的可能作用已通过两亲性活化的α-氨基酸（外消旋和手性非外消旋形式）的催化聚合进行了探索，它们具有自在气-液界面处组装成二维（2D）有序微晶。作为模型系统，我们研究了N-ε-硬脂酰基-赖氨酸硫代乙基酯（C_18-TE-Lys），γ-硬脂基-谷氨酸硫代乙基酯（C_18-TE-Glu），N_α-硬脂基-谷氨酸的N-羧基酸酐（ C_18-Glu NCA）和γ-硬脂基-谷氨酸硫酸（C_18-硫代-Glu）。根据水面上的原位掠入射X射线衍射测量结果，（R，S）-C_18-TE-Lys，（R，S）-C_18-TE-Glu和（R，S）-C_18-Glu- NCA两栖动物自组装成有序的外消旋2D晶体。在将适当的催化剂注入水亚相中之后，在空气-水溶液界面处获得了2-12个单位长的寡肽。发现由（R，S）-C_18-TE-Lys和（R，S）-C_18-TE-Glu生成的具有同手性序列的寡肽的实验相对丰度，通过质谱对对映选择性氘标记的样品进行了测定明显大于由随机聚合的（R，S）C_18-thio-Glu所获得的分子量。在C_18-Glu-NCA的非外消旋混合物的聚合反应中，由于外消旋2D微晶中的单体分子经过定向，使得在通过滑移对称性关联的杂手性分子之间发生反应，从而产生杂手性寡肽，而对映异构体却发生了有效的手性扩增过量地，在庚型晶体中，产生单手性的寡肽。

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