Polytheonamide B is by far the largest non-ribosomal peptide known at present, and displays extraordinary cytotoxicity (EC50 = 68 pg mlâ1, mouse leukaemia P388 cells). Its 48 amino-acid residues include a variety of non-proteinogenic d- and l-amino acids, and the absolute stereochemistry of these amino acids alternate in sequence. These structural features induce the formation of a stable β-strand-type structure, giving rise to an overall tubular structure over 30 Ã
in length. In a biological setting, this fold is believed to transport cations across the lipid bilayer through a pore, thereby acting as an ion channel. Here, we report the first chemical construction of polytheonamide B. Our synthesis relies on the combination of four key stages: syntheses of non-proteinogenic amino acids, a solid-phase assembly of four fragments of polytheonamide B, silver-mediated connection of the fragments and, finally, global deprotection. The synthetic material now available will allow studies of the relationships between its conformational properties, channel functions and cytotoxicity. Polytheonamide B is a large non-ribosomal peptide with very high bioactivity. The synthesis described here includes the first preparation of several non-proteinogenic amino acids and a general coupling strategy for large non-natural peptides. The synthesis is a key step necessary to understand and utilize the bioactivity of this and similar compounds.
聚糖
酰胺 B 是目前已知的最大的非
核糖体肽,具有非凡的细胞毒性(
EC50 = 68 pg mlâ1, 小鼠白血病 P388 细胞)。它的 48 个
氨基酸残基包括多种非蛋白原性 d 和 l
氨基酸,这些
氨基酸的绝对立体
化学结构依次交替。这些结构特征促使形成稳定的δ-strand 型结构,从而形成长度超过 30 Ã 的整体管状结构。在
生物环境中,这种折叠结构被认为可以通过一个孔隙在脂质双分子层中运输阳离子,从而起到离子通道的作用。在此,我们首次报告了聚神
酰胺 B 的
化学结构。我们的合成依赖于四个关键阶段的结合:非蛋白源
氨基酸的合成、聚草
酰胺 B 四个片段的固相组装、
银介导的片段连接以及最后的全局
脱保护。现在可用的合成材料将有助于研究其构象特性、通道功能和细胞毒性之间的关系。聚神
酰胺 B 是一种大型非
核糖体
多肽,具有极高的
生物活性。本文描述的合成包括首次制备几种非蛋白源
氨基酸和大型非
天然肽的一般偶联策略。该合成是了解和利用该化合物及类似化合物
生物活性的关键一步。