Temporin family is one of the largest among antimicrobial peptides (AMPs), which act mainly by penetrating and disrupting the bacterial membranes. To further understand the relationship between the physical-chemical properties and their antimicrobial activity and selectivity, an analogue of Temporin L, [Nle¹, DLeu⁹, DLys¹⁰]TL (Nle-Phe-Val-Pro-Trp-Phe-Lys-Phe-dLeu-dLys-Arg-Ile-Leu-CONH₂) has been developed in the present work. The design strategy consisted of the addition of a norleucine residue at the N-terminus of the lead peptide sequence, [dLeu⁹, dLys¹⁰]TL, previously developed by our group. This modification promoted an increase of peptide hydrophobicity and, interestingly, more efficient activity against both Gram-positive and Gram-negative strains, without affecting human keratinocytes and red blood cells survival compared to the lead peptide. Thus, this novel compound was subjected to biophysical studies, which showed that the peptide [Nle¹, dLeu⁹, dLys¹⁰]TL is unstructured in water, while it adopts β-type conformation in liposomes mimicking bacterial membranes, in contrast to its lead peptide forming α-helical aggregates. After its aggregation in the bacterial membrane, [Nle¹, dLeu⁹, dLys¹⁰]TL induced membrane destabilization and deformation. In addition, the increase of peptide hydrophobicity did not cause a loss of anti-inflammatory activity of the peptide [Nle¹, dLeu⁹, dLys¹⁰]TL in comparison with its lead peptide. In this study, our results demonstrated that positive net charge, optimum hydrophobic−hydrophilic balance, and chain length remain the most important parameters to be addressed while designing small cationic AMPs.

中文翻译：

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具有双重抗菌和抗炎活性的合成两亲性 β-Sheet Temporin 衍生肽

Temporin 家族是抗菌肽 (AMP) 中最大的家族之一，其主要通过穿透和破坏细菌膜起作用。为了进一步了解物理化学性质与其抗菌活性和选择性之间的关系，Temporin L、[Nle ¹、DLeu ⁹、DLys ¹⁰ ]TL 的类似物（Nle-Phe-Val-Pro-Trp-Phe-Lys- Phe-dLeu-dLys-Arg-Ile-Leu-CONH ₂ ) 已在当前工作中开发。设计策略包括在前导肽序列的 N 末端添加正亮氨酸残基 [dLeu ⁹ , dLys ¹⁰]TL，之前由我们小组开发。这种修饰促进了肽疏水性的增加，有趣的是，与先导肽相比，对革兰氏阳性和革兰氏阴性菌株的活性更有效，而不会影响人类角质形成细胞和红细胞的存活。因此，对这种新型化合物进行了生物物理研究，结果表明肽 [Nle ¹ , dLeu ⁹ , dLys ¹⁰ ]TL 在水中是非结构化的，而它在模拟细菌膜的脂质体中采用 β 型构象，与其先导形成对比。肽形成α-螺旋聚集体。在细菌膜中聚集后，[Nle ¹ , dLeu ⁹ , dLys ¹⁰]TL 诱导膜失稳和变形。此外，与其先导肽相比，肽疏水性的增加不会导致肽[Nle ¹、dLeu ⁹、dLys ¹⁰ ]TL的抗炎活性丧失。在这项研究中，我们的结果表明，正净电荷、最佳疏水-亲水平衡和链长仍然是设计小型阳离子 AMP 时需要解决的最重要参数。