Gastrin-releasing peptide (GRP) is a mammalian neuropeptide that shares structural and functional similarities with the amphibian peptide bombesin. It is widely distributed in the gastrointestinal tract and pancreas, where it is primarily localized in neural structures. GRP exerts potent effects on the release of various gastroentero-pancreatic (GEP) hormones, including insulin, glucagon, and pancreatic polypeptide (PP). Studies in multiple species have demonstrated that GRP can stimulate basal hormone secretion and enhance glucose-induced insulin release, although its effects may vary depending on the experimental conditions and species examined.

GRP influences the endocrine pancreas through both direct and indirect mechanisms. In isolated pancreatic preparations, GRP has been shown to dose-dependently stimulate insulin and PP secretion while inhibiting somatostatin release. The peptide's actions are mediated through interactions with specific receptors on islet cells, though the precise signaling pathways remain under investigation. Anatomical studies reveal GRP-containing nerve fibers in close proximity to pancreatic islets, suggesting a role in local neural regulation of hormone secretion. Species differences exist in GRP's potency and spectrum of activity, as well as in the mechanisms governing its release, highlighting the complexity of its regulatory functions in the endocrine pancreas.

• Mcdonald TJ, Jörnvall H, Nilsson G, et al. Characterization of a gastrin releasing peptide from porcine non-antral gastric tissue. Biochem Biophys Res Commun. 1979;90(1):227-33.
• McDonald TJ, Houghton P, Challis JR, Hramiak IM. The effect of gastrin-releasing peptide on the endocrine pancreas. Ann N Y Acad Sci. 1988;547:242-54. doi: 10.1111/j.1749-6632.1988.tb23893.x. PMID: 3071222.

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。