Peptaibs是抗蛋白水解的,膜活性肽。它们非常稳定的螺旋3D结构是其生物活性的关键。它们可以将自己插入脂质双层作为桶形板条,或者像地毯一样躺在它的表面上,取决于它们的长度和脂质双层的厚度。中等长度的肽对于研究肽-膜相互作用特别感兴趣,因为它们的长度允许它们根据膜厚度采用任一方向。which,反过来,甚至可能导致选择性增强。电子顺磁共振(EPR)是用于此目的的选择技术,但它需要合成自旋标记的中等长度的肽,which,反过来,受到序列中Cα-四取代残基反应性差的阻碍。经过几年的反复试验,我们现在能够为成功合成含硝基氧化合物的肽类提供最先进的建议,避免删除序列,副反应和困难的纯化步骤。在这里,我们描述了我们的策略及其在最近发现的自旋标记类似物合成中的应用,自然,中等长度的peptaibol十五台宾。我们研究了五代aibin及其类似物的抗肿瘤活性,发现对人类三阴性乳腺癌和卵巢癌有效的细胞毒性。最后,我们对肽构象偏好和膜相互作用的分析证明,十五碳氢自旋标记不会改变天然序列的生物学特征,适合进一步的EPR研究。含硝基氧的十五碳素,以及本文所述的合成策略,将有助于阐明中等长度的肽-膜相互作用的机制。
Peptaibols are proteolysis-resistant, membrane-active peptides. Their remarkably stable helical 3D-structures are key for their bioactivity. They can insert themselves into the lipid bilayer as barrel staves, or lay on its surface like carpets, depending on both their length and the thickness of the lipid bilayer. Medium-length peptaibols are of particular interest for studying the peptide-membrane interaction because their length allows them to adopt either orientation as a function of the membrane thickness, which, in turn, might even result in an enhanced selectivity. Electron paramagnetic resonance (EPR) is the election technique used to this aim, but it requires the synthesis of spin-labeled medium-length peptaibols, which, in turn, is hampered by the poor reactivity of the Cα-tetrasubstituted residues featured in their sequences. After several years of trial and error, we are now able to give state-of-the-art advice for a successful synthesis of nitroxide-containing peptaibols, avoiding deleted sequences, side reactions and difficult purification steps. Herein, we describe our strategy and itsapplication to the synthesis of spin-labeled analogs of the recently discovered, natural, medium-length
peptaibol pentadecaibin. We studied the antitumor activity of pentadecaibin and its analogs, finding potent cytotoxicity against human triple-negative breast cancer and ovarian cancer. Finally, our analysis of the peptide conformational preferences and membrane interaction proved that pentadecaibinspin-labeling does not alter the biological features of the native sequence and is suitable for further EPR studies. The nitroxide-containing pentadecaibins, and their synthetic strategy described herein, will help to shed light on the mechanism of the peptide-membrane interaction of medium-length peptaibols.