The widespread abuse of antibiotics has led to the use of antimicrobial peptides (AMPs) as a replacement for the existing conventional therapeutic agents for combating microbial infections. The broad-spectrum activity and the resilient nature of AMPs has mainly aggrandized their utilization. Here, we report the design of non-toxic, non-hemolytic and salt tolerant undecapeptides (AMP21-24), derived by modification of a peptide P5 (NH2-LRWLRRLCONH2) reported earlier by our group. Our results depict that the designed peptides show potency against several bacterial as well as fungal strains. Circular dichroism (CD) spectroscopy in combination with molecular dynamic (MD) simulations confirm that the peptides are unstructured. Intrinsic tryptophan fluorescence quenching as well as interaction studies using isothermal calorimetry (ITC) of these peptides in the presence of biological microbial membrane mimics establish the strong microbial membrane affinity of these AMPs. Membrane permeabilization assay and cytoplasmic membrane depolarization studies of Pseudomonas aeruginosa and Candida albicans in the presence of AMPs also hint towards the AMP-membrane interactions. Leakage of calcein dye from membrane mimic liposomes, live cell NMR and field emission scanning electron microscopy (FESEM) studies suggest that the AMPs may be primarily involved in membrane perturbation leading to release of intracellular substances resulting in subsequent microbial cell death. Confocal laser scanning microscopy (CLSM) shows localization of the peptides throughout the cell, indicating the possibility of secondary mode of actions. Electrostatic interactions seem to govern the preferential binding of the AMPs to the microbial membranes in comparison to the mammalian membranes as seen from the MD simulations.

中文翻译：

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合理设计的抗菌肽：深入了解11种残留肽抵抗微生物感染的机理。

抗生素的广泛滥用已导致使用抗菌肽（AMPs）来替代现有的常规抗微生物感染治疗剂。AMP的广谱活动和弹性性质主要是提高了它们的利用率。在这里，我们报告了无毒，无溶血和耐盐的十一肽的设计（AMP21-24），该肽是由我们小组较早前报道的肽P5（NH2-LRWLRRLCONH2）修饰而衍生的。我们的结果表明，设计的肽对多种细菌和真菌菌株均具有效力。圆二色性（CD）光谱结合分子动力学（MD）模拟证实了肽是非结构化的。固有色氨酸荧光猝灭以及在生物微生物膜模拟物存在下使用这些肽的等温量热法（ITC）进行的相互作用研究建立了这些AMP的强微生物膜亲和力。在存在AMP的情况下铜绿假单胞菌和白色念珠菌的膜透化测定和细胞质膜去极化研究也提示AMP膜相互作用。钙黄绿素染料从膜模拟脂质体泄漏，活细胞NMR和场发射扫描电子显微镜（FESEM）研究表明，AMPs可能主要参与膜微扰，导致细胞内物质释放，导致随后的微生物细胞死亡。共聚焦激光扫描显微镜（CLSM）显示了肽在整个细胞中的定位，表明采取第二种行动方式的可能性。如从MD模拟中所见，与哺乳动物膜相比，静电相互作用似乎决定了AMP与微生物膜的优先结合。