Abstract

Cecropin A (1–7) is a cationic antimicrobial peptide which contain lots of basic amino acids. To understand the effect of basic amino acids on cecropin A (1–7), analogues CA2, CA3 and CA4 which have more arginine or lysine at the N-terminal or C-terminal were designed and synthesized. The interaction of cecropin A (1–7) and its analogs with DNA was studied using ultraviolet–visible spectroscopy, fluorescence spectroscopy and circular dichroism spectroscopy. Multispectral analysis showed that basic amino acids improved the interaction between the analogues and DNA. The interaction between CA4 and DNA is most pronounced. Fluorescence spectrum indicated that Ksv value of CA4 is 1.19 × 10⁵ L mol⁻¹ compared to original peptide cecropin A (1–7) of 3.73 × 10⁴ L mol⁻¹. The results of antimicrobial experiments with cecropin A (1–7) and its analogues showed that basic amino acids enhanced the antimicrobial effect of the analogues. The antimicrobial activity of CA4 against E. coli was eightfold higher than that of cecropin A (1–7). The importance of basic amino acid in peptides is revealed and provides useful information for subsequent studies of antimicrobial peptides.

Graphical Abstract

中文翻译：

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通过多光谱方法分析天蚕素 A (1–7) 类似物与 DNA 的相互作用

摘要

Cecropin A (1–7) 是一种阳离子抗菌肽，含有大量碱性氨基酸。为了了解碱性氨基酸对天蚕素 A (1–7) 的影响，设计并合成了 N 端或 C 端有更多精氨酸或赖氨酸的类似物 CA2、CA3 和 CA4。使用紫外可见光谱、荧光光谱和圆二色光谱研究了天蚕素 A (1-7) 及其类似物与 DNA 的相互作用。多光谱分析表明碱性氨基酸改善了类似物和 DNA 之间的相互作用。CA4 和 DNA 之间的相互作用最为明显。荧光光谱表明，CA4 的 Ksv 值为 1.19 × 10 ⁵ L mol ^-1，而原始肽天蚕素 A (1-7) 的 Ksv 值为 3.73 × 10 ⁴ L mol ^-1。天蚕素 A (1-7) 及其类似物的抗菌实验结果表明，碱性氨基酸增强了类似物的抗菌作用。CA4 对大肠杆菌的抗菌活性比天蚕素 A 高八倍 (1-7)。揭示了碱性氨基酸在肽中的重要性，为后续抗菌肽的研究提供了有用的信息。

图形概要