The artificial cationic antimicrobial peptide KLKL5KLK (H-KLKLLLLLKLK-NH₂) is a synthetic undecapeptide derived from sapecin B, modified to enhance activity. It exhibits structural features typical of cationic antimicrobial peptides, characterized by a palindromic sequence with alternating hydrophobic and cationic residues. This design promotes interactions with biological membranes and cell surfaces.

KLKL5KLK demonstrates the ability to enhance antigen association with antigen-presenting cells in vitro and forms a transient antigen depot at the injection site in vivo. The peptide retains its immuno-enhancing properties despite C-terminal amidation or synthesis with D-amino acids, indicating that its activity depends primarily on amino acid side chain sequence rather than backbone stereospecificity. It predominantly induces a TH2-type immune polarization profile when co-administered with proteinaceous or peptide-based antigens, as evidenced by elevated IL-4 and IL-5 production and sustained antibody responses.

• Fritz JH, Brunner S, Birnstiel ML, Buschle M, Gabain Av, Mattner F, Zauner W. The artificial antimicrobial peptide KLKLLLLLKLK induces predominantly a TH2-type immune response to co-injected antigens. Vaccine. 2004 Sep 3;22(25-26):3274-84. doi: 10.1016/j.vaccine.2004.03.007. PMID: 15308350.

三氟乙酸（TFA）是一种强酸，常用于从固相树脂中裂解合成的多肽，也可用于提高多肽纯化步骤中的HPLC性能。默认情况下，定制的多肽是以冻干的TFA盐的形式交付的，其中TFA的含量可能高达10-45%。

定制多肽中的TFA可能会导致后续检测数据出现无法解释的差异。例如，nM浓度的TFA已被证明会干扰细胞实验，在某些情况下会抑制细胞增殖，而在其他情况下会增加细胞活力。

TFA去除服务推荐用于:

• 将用于细胞试验的多肽
• 将被用作原料药或制成品的多肽
• 含有大量碱性残基的亲水多肽

干品多肽的重量中不仅仅包含多肽，还包含有一些非肽的组份，如水、被吸收的溶剂、配位离子和盐等。肽的净含量是指肽在其中的重量百分比，这个百分比的数值范围很大，可能从50%到90%，取决于纯度、序列以及合成和纯化的方法，不要将肽的净含量和肽的纯度混为一谈，他们是两个完全不同的概念。纯度通常是通过HPLC测定的。纯度定义的是多肽样品中含正确序列的组分的百分比，而肽的净含量是指样品中肽类物质相对于总物质所占的百分比，肽的净含量通常是氨基酸组分分析或紫外分光法测定的，这个信息主要是在一些对肽的浓度很敏感的实验中，对计算肽的浓度是很重要的。