Abstract：
Chem-KVL is a tandem repeating peptide, with 14 amino acids that was modified based on a short peptide from a fragment of the human host defense protein chemerin. Chem-KVL increases cationicity and hydrophobicity and shows broad-spectrum antibacterial activity. To determine the molecular determinants of Chem-KVL and whether staple-modified Chem-KVL would improve antibacterial activity and protease stability or decrease cytotoxicity, we combined alanine and stapling scanning, and designed a series of alanine and staple-derived Chem-KVL peptides, termed Chem-A1 to Chem-A14 and SCL-1 to SCL-7. We next examined their antibacterial activity against several gram-positive and gram-negative bacteria, their proteolytic stability, and their cytotoxicity. Ala scanning of Chem-KVL suggested that both the positively charged residues (Lys and Arg) and the hydrophobic residues (Lue and Val) were critical for the antibacterial activities of Chem-KVL peptide. Of note, Chem-A4 was able to remarkably inhibit the growth of gram-positive and gram-negative bacteria when compared to the original peptide. And the antibacterial activities of stapled SCL-4 and SCL-7 were several times higher than those of the linear peptide against gram-positive and gram-negative bacteria. Stapling modification of peptides resulted in increased helicity and protein stability when compared with the linear peptide. These stapled peptides, especially SCL-4 and SCL-7, may serve as the leading compounds for further optimization and antimicrobial therapy.
摘要：
Chem-KVL是一种串联重复肽，具有14个氨基酸，这些氨基酸是基于人类宿主防御蛋白chemerin片段的短肽进行修饰的。Chem-KVL增加阳离子性和疏水性并显示广谱抗菌活性。为了确定Chem-KVL的分子决定因素，以及钉修饰的Chem-KVL是否会提高抗菌活性和蛋白酶稳定性或降低细胞毒性，我们结合了丙氨酸和装订扫描，并设计了一系列丙氨酸和订书钉衍生的Chem-KVL肽，称为Chem-A1至Chem-A14和SCL-1至SCL-7。接下来我们检查了它们对几种革兰氏阳性和革兰氏阴性细菌的抗菌活性，它们的蛋白水解稳定性，和它们的细胞毒性。Chem-KVL的Ala扫描表明，带正电荷的残基（Lys和Arg）和疏水性残基（Lue和Val）对于Chem-KVL肽的抗菌活性至关重要。值得注意的是，当与原始肽相比时,Chem-A4能够显著抑制革兰氏阳性和革兰氏阴性细菌的生长。钉合的SCL-4和SCL-7对革兰氏阳性菌和革兰氏阴性菌的抗菌活性是线性肽的几倍。当与线性肽相比时,肽的装订修饰导致增加的螺旋度和蛋白质稳定性。这些装订肽，特别是SCL-4和SCL-7,可以作为进一步优化和抗菌治疗的先导化合物。
