Antimicrobial peptides are widely studied as an alternative to traditional antibiotics. However, they are difficult to develop, as multiple factors influence their potency and selectivity toward bacterial cells. In this paper, we investigate three simplified model peptides that bear crown ethers, and the effects of simple structural modifications (peptide length and crown ether ring size) on their secondary structures and their permeabilizing activity on living cells and model membranes made with egg yolk phosphatidylcholine or 1-palmitoyl-2-oleoylphosphatidylglycerol. Circular dichroism studies show that the peptide length and the crown ether ring size do influence the conformation, but no trend could be determined from the results. Permeabilization studies with model membranes and with red blood cells demonstrated that from 13 residues to 16 residues, there is a gradual increase in activity as the peptides get longer. However, the shortest tested analogs, with 12 residues, also exhibited an increase in activity caused by the removal of one amino acid that was bearing a crown ether. Permeabilization assays showed that larger ring size analogs showed higher hemolytic activities. Altogether, the results reported help design new and more selective antimicrobial peptides.

中文翻译：

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冠醚修饰的肽：长度和冠环大小对膜相互作用的影响。

抗菌肽已被广泛研究作为传统抗生素的替代品。然而，由于多种因素影响它们对细菌细胞的效力和选择性，因此它们难以开发。在本文中，我们研究了三种带有冠醚的简化模型肽，以及简单的结构修饰（肽长度和冠醚环大小）对其二级结构的影响以及它们对蛋黄磷脂酰胆碱制成的活细胞和模型膜的透化活性。或1-棕榈酰基-2-油酰基磷脂酰甘油。圆二色性研究表明，肽的长度和冠醚环的大小确实会影响构象，但无法从结果确定趋势。用模型膜和红细胞进行的通透性研究表明，从13个残基增加到16个残基，随着肽变得更长，活性逐渐增加。然而，最短的测试的类似物具有12个残基，由于去除了一个带有冠醚的氨基酸而引起的活性增加。通透性测定表明，较大的环类似物显示较高的溶血活性。总之，所报告的结果有助于设计新的和更具选择性的抗菌肽。通透性测定表明，较大的环类似物显示较高的溶血活性。总之，所报告的结果有助于设计新的和更具选择性的抗菌肽。通透性测定表明，较大的环类似物显示较高的溶血活性。总之，所报告的结果有助于设计新的和更具选择性的抗菌肽。