Ampetoids as Biostable Functional Mimics of Antimicrobial Peptides

描述（由申请人提供）：我们建议创建和研究用于抗菌应用的新仿生低聚物家族。特别是，我们的目标是创造生物稳定的、功能性的天然抗菌肽（AMP）模拟物，它是从人类到细菌等多种生物体宿主防御系统中不可或缺的有效组成部分。通过优先结合并破坏或渗透细菌细胞膜，这些表面活性肽能够杀死多种微生物。许多也是有选择性的，不会对哺乳动物细胞造成伤害。这种杀伤机制虽然尚不完全清楚，但足够普遍，以至于细菌在数百万年的时间里无法进化出对 AMP 的抵抗力。因此，良好的 AMP 功能模拟物有望成为一类新型抗生素化合物，它可以直接在溶液中发挥作用，也可以附着在生物医学设备的表面来避免感染。我们建议创建 AMP 的非天然模拟物，因为肽本身容易蛋白水解，因此在体内降解过快，而且因为肽在体内通常具有免疫原性。特别是，我们的新型模拟物将基于两亲性、序列特异性寡-N-取代甘氨酸（“类肽”）。类肽在结构上与肽非常相似，但具有蛋白酶抗性。它们可以通过高产固相方案轻松合成，从而可以轻松掺入仿生侧链。此外，类肽可以被设计成形成稳定的仿生螺旋，在水和生物膜环境中保持其折叠结构，并且具有高度的抗变性能力。在初步工作中，我们已经证明，旨在模拟抗菌肽的两亲序列模式和螺旋结构的某些类肽序列（9-17mers）是有效且选择性的抗菌剂（针对大肠杆菌的 MIC ~ 4 µM，针对枯草芽孢杆菌的 820 nM，在大肠杆菌 MIC 时溶血可忽略不计）。我们建议进一步研究和开发这些化合物，方法是（1）通过对具有不同效力/选择性特征的密切相关类肽的“基础集”进行详细的生物物理学研究，探索结构功能关系和作用机制，（2）创建模仿天然AMP结构基序的新型类肽，包括脂化、环化和扭结的类肽； （3）测试其对抗生素耐药细菌的抗生素活性以及对人体细胞毒性的早期研究。

DESCRIPTION (provided by applicant): We propose to create and study a new family of biomimetic oligomers for antibacterial applications. In particular, we aim to create biostable, functional mimics of natural antimicrobial peptides (AMPs), which are an integral and effective part of the host-defense systems of myriad organisms ranging from humans to bacteria. By preferentially binding to and disrupting or permeating bacterial cell membranes, these surface- active peptides are able to kill a broad spectrum of microorganisms. Many are also selective, causing no harm to mammalian cells. The killing mechanism, while imperfectly understood, is sufficiently general that bacteria have been unable to evolve resistance to AMPs over millions of years. Thus, good functional mimics of AMPs hold forth the promise of serving as a new class of antibiotic compounds, which could act in solution directly or be tethered to the surfaces of biomedical devices to stave off infection. We propose to create non-natural mimics of AMPs, since peptides themselves are vulnerable to proteolysis and hence degrade too rapidly in the body, and moreover because peptides are often immunogenic in vivo. In particular, our novel mimics will be based on amphipathic, sequence-specific oligo-N-substituted glycines ("peptoids"). Peptoids are quite similar in structure to peptides, yet are protease-resistant. They are easily synthesized by a high-yielding, solid-phase protocol that allows the easy incorporation of biomimetic side chains. Moreover, peptoids can be designed to form stable, biomimetic helices that keep their folded structure in both aqueous and biomembrane environments, and which are highly resistant to denaturation. In preliminary work, we have shown that certain peptoid sequences (9-17mers) designed to mimic the amphipathic sequence patterning and helical structure of antimicrobial peptides are potent and selective antibacterials (MIC ~ 4 ¿M against E. coli and 820 nM against B. subtilis, with negligible hemolysis at the E. coli MIC). We propose to further study and develop these compounds, by (1) exploring structure-function relationships and mechanism(s) of action through detailed biophysical studies of a "basis set" of closely related peptoids with differing potency/selectivity profiles, (2) creating novel peptoids that mimic structural motifs of natural AMPs, including peptoids that are lipidated, cyclized, and kinked; (3) testing their antibiotic activity against antibiotic-resistant bacteria as well as early-stage investigation of their toxicity to human cells.