Institute of Biotechnology and Department of Medical Science, National Tsing Hua University, Hsinchu 300, Taiwan.
Institute of Biotechnology and Department of Medical Science, National Tsing Hua University, Hsinchu 300, Taiwan; Department of Neurology, National Taiwan University Hospital Hsinchu Branch, Hsinchu 300, Taiwan.
J Colloid Interface Sci. 2019 Jan 1;533:492-502. doi: 10.1016/j.jcis.2018.08.042. Epub 2018 Aug 14.
Release of lipopolysaccharides (LPS) from bacteria into bloodstream may cause serious unwanted stimulation of the host immune system. P-113 is a clinically active histidine-rich antimicrobial peptide. Nal-P-113, a β-naphthylalanine-substituted P-113, is salt-resistant but has limited LPS neutralizing activity. We suspected the size and shape of the non-natural bulky amino acid may affect its LPS neutralizing activity. Herein, antimicrobial, LPS neutralizing, and antiproteolytic effects of phenylalanine- (Phe-P-113), β-naphthylalanine- (Nal-P-113), β-diphenylalanine- (Dip-P-113), and β-(4,4'-biphenyl)alanine- (Bip-P-113) substituted P-113 were studied.
Structure-activity relationships of P-113, Phe-P-113, Nal-P-113, Dip-P-113, and Bip-P-113 were evaluated using antimicrobial activity assays, serum proteolytic assays, peptide-induced permeabilization of large unilamellar vesicles, zeta potential measurements, dynamic light scattering measurement of LPS aggregation, and Limulus amebocyte lysate assays for measuring LPS neutralization. In vitro and in vivo LPS neutralizing activities were further confirmed by LPS-induced inflammation inhibition in an endotoxemia mouse model.
Bip-P-113 and Dip-P-113 had the longest and widest non-nature amino acids, respectively. Bip-P-113 enhanced salt resistance, serum proteolytic stability, peptide-induced permeabilization, zeta potential measurements, LPS aggregation, and in vitro and in vivo LPS neutralizing activities. These results could help design novel antimicrobial peptides that have enhanced stability in vivo and that can have potential therapeutic applications.
细菌释放到血液中的脂多糖（LPS）可能会引起宿主免疫系统的严重不良反应。P-113 是一种具有临床活性的组氨酸丰富的抗菌肽。Nal-P-113 是一种β-萘丙氨酸取代的 P-113，具有耐盐性，但 LPS 中和活性有限。我们怀疑非天然大体积氨基酸的大小和形状可能会影响其 LPS 中和活性。在此，研究了苯丙氨酸（Phe-P-113）、β-萘丙氨酸（Nal-P-113）、β-二苯丙氨酸（Dip-P-113）和β-（4,4'-联苯）丙氨酸（Bip-P-113）取代的 P-113 的抗菌、LPS 中和和抗蛋白水解作用。
使用抗菌活性测定、血清蛋白水解测定、肽诱导大单室囊泡通透、Zeta 电位测量、LPS 聚集的动态光散射测量以及测定 LPS 中和的鲎变形细胞溶解物测定，评估了 P-113、Phe-P-113、Nal-P-113、Dip-P-113 和 Bip-P-113 的构效关系。通过在脂多糖血症小鼠模型中抑制 LPS 诱导的炎症，进一步证实了这些肽在体内和体外的 LPS 中和活性。
Bip-P-113 和 Dip-P-113 分别具有最长和最宽的非天然氨基酸。Bip-P-113 增强了耐盐性、血清蛋白水解稳定性、肽诱导的通透、Zeta 电位测量、LPS 聚集以及体外和体内 LPS 中和活性。这些结果有助于设计具有增强体内稳定性和潜在治疗应用的新型抗菌肽。
