蛋清源活性肽如ACE抑制肽等要在体内发挥活性，须以其完整形式被小肠吸收进入体内。目前鉴定的活性肽长度一般在3个氨基酸以上，然而这部分寡肽的体内完整吸收性及吸收机制尚不明确，是活性肽研究领域急需解决的关键问题。本项目利用Caco-2细胞膜和大鼠外翻肠囊模型，鉴定蛋清源可完整吸收的寡肽，结合人工设计肽序列，明确肽的结构与完整吸收关系；研究蛋清寡肽完整吸收的动力学特征，及其对pH梯度、Na+浓度的依赖性，以及完整吸收过程伴随的细胞内pH、电位和细胞膜电位的动态变化等生理特性；利用荧光标记技术，通过共聚焦激光显微镜和透射电子显微镜观察寡肽的完整吸收途径和过程，结合吸收通路抑制剂，明确寡肽的完整吸收通路，并以高浓度蛋清寡肽胁迫处理肠细胞或灌胃大鼠，分析差异表达基因和蛋白，从细胞和分子水平阐述蛋清寡肽的完整吸收途径和机制。本项目研究可为寡肽的小肠完整吸收提供证明，为活性肽的科学研究和加工应用奠定基础。

To exert bioactivity in vivo, egg white-derived bioactive peptides, i.e. ACE-inhibitory peptides, must be absorbed in intact form. It is known that the most of bioactive peptides identified from food protein have more than three amino acids, but their absorption mechanism is still obscure. This project aims to investigate the transport of egg white-derived oligopeptides through intestinal epithelium using Caco-2 cell monolayers and everted rat intestinal sacs. First, the peptides that can be absorbed in intact form will be identified. Based on the absorbed peptides, as well as artificial designed oligopeptides, the relationship between the structure and transport of peptides will be studied. Second, the physiological properties, including transport kinetic characteristics, dependence to pH gradient and sodium salt, dynamic changes of intracellular pH value, potential and membrane potential and so on during the transport process of transport of oligopeptides will be determined. Third, confocal laser scanning microscopy and transmission electron microscopy are used to observe the transport route and process of some oligoppetides that labled with fluorescent molecules. Some transport inhibitors will be also used to verify the transport pathways of oligopeptides. Moreover, the models of enterocytes or rats that incubated with high concentration of egg white-derived oligopeptides will be established. Then, the differentially expressed genes and proteins compared to control group will be identified using gene chips and 2-D gel electrophoresis. It is possible to provide evidences and explore the biological mechanism of the transport of egg white-derived oligopeptides from celland molecular levels. This project is expected to contribute the understanding of the intact transport of food derived bioactive oligopeptides.