Sex peptide (SP), also known as ACP70A, is a 36-amino acid peptide synthesized in the male accessory glands of Drosophila melanogaster. It functions as a pheromone transferred to females during mating, where it modulates reproductive behavior by increasing oviposition and reducing receptivity to subsequent mating. The peptide exhibits structural features including hydroxyproline residues and binds to specific sites in the female nervous system and genital tract.

DUP99B, a related 31-amino acid peptide isolated from the male ejaculatory duct, shares high C-terminal homology with SP and induces identical postmating responses in females. It is glycosylated at an NDT consensus site and contains a disulfide bond, with its precursor encoded by a gene localized in cytological region 99B. Both peptides are considered members of a sex-peptide gene family, likely originating from gene duplication, though differences in their N-terminal regions and modifications suggest potential functional specialization.

• Kubli E. Sex-peptides: seminal peptides of the Drosophila male. Cell Mol Life Sci. 2003 Aug;60(8):1689-704. doi: 10.1007/s00018-003-3052. PMID: 14504657; PMCID: PMC11146071.
• Saudan P, Hauck K, Soller M, Choffat Y, Ottiger M, Spörri M, Ding Z, Hess D, Gehrig PM, Klauser S, Hunziker P, Kubli E. Ductus ejaculatorius peptide 99B (DUP99B), a novel Drosophila melanogaster sex-peptide pheromone. Eur J Biochem. 2002 Feb;269(3):989-97. doi: 10.1046/j.0014-2956.2001.02733.x. PMID: 11846801.
• Scheunemann L, Lampin-Saint-Amaux A, Schor J, Preat T. A sperm peptide enhances long-term memory in female Drosophila. Sci Adv. 2019 Nov 20;5(11):eaax3432. doi: 10.1126/sciadv.aax3432. PMID: 31799390; PMCID: PMC6867886.

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。