Nal-P-113 is a synthetic antimicrobial peptide derived from P-113 (AKRHHGYKRKFH-NH2), a 12-amino-acid histidine-rich peptide originating from the salivary protein histatin 5. In Nal-P-113, the histidine residues at positions 4, 5, and 12 are replaced with β-naphthylalanine, a bulky amino acid, yielding the sequence Ac-AKR-Nal-Nal-GYKRKF-Nal-NH2. This structural modification confers resistance to high-salt conditions and degradation in biological fluids such as PBS, saliva, and serum, where the parent peptide P-113 is highly degradable.

Nal-P-113 exhibits bactericidal activity by permeabilizing and/or forming pores within cytoplasmic membranes, and its antimicrobial and anti-biofilm effects have been confirmed in in vitro studies. The peptide also displays concentration-dependent modulation of immune-inflammatory mediators, including IL-1β and TNF-α. Its ability to retain activity in physiological environments distinguishes it from many antimicrobial peptides that are effective in vitro but susceptible to degradation in vivo.

• Wang HY, Lin L, Fu W, Yu HY, Yu N, Tan LS, Cheng JW, Pan YP. Preventive effects of the novel antimicrobial peptide Nal-P-113 in a rat Periodontitis model by limiting the growth of Porphyromonas gingivalis and modulating IL-1β and TNF-α production. BMC Complement Altern Med. 2017 Aug 29;17(1):426. doi: 10.1186/s12906-017-1931-9. PMID: 28851350; PMCID: PMC5576277.
• Wang HY, Lin L, Tan LS, Yu HY, Cheng JW, Pan YP. Molecular pathways underlying inhibitory effect of antimicrobial peptide Nal-P-113 on bacteria biofilms formation of Porphyromonas gingivalis W83 by DNA microarray. BMC Microbiol. 2017 Feb 17;17(1):37.

三氟乙酸（Trifluoroacetic acid，简称 TFA）是高效液相色谱（简称 HPLC）纯化过程中常用的反离子。TFA 的存在可能会对肽的净重量、外观及溶解度产生影响，具体如下：

对净重量的影响：TFA 盐会增加产物的总质量。在大多数情况下，肽的含量占总重量的 80% 以上，剩余部分则为 TFA。

对溶解度的影响：TFA 盐通常能提高肽在水溶液中的溶解度。

在生物检测中的影响：对于大多数标准的体外检测，残留的 TFA 水平一般不会造成干扰。但需注意，在高灵敏度的细胞研究或生化研究中，需关注其存在可能带来的影响。

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。