驼乳乳铁蛋白DPP-IV抑制肽的筛选验证及其防治糖尿病潜在作用机制探究

目的:结合生物信息学，从驼乳乳铁蛋白（Lactoferrin，LF）中筛选DPP-IV（Dipeptidyl peptidase IV，DPP-IV）抑制肽，并利用网络药理学探讨筛选肽段对糖尿病的潜在作用机制。方法:利用BIOPEP网站模拟酶切LF序列产生多条肽段，结合多肽数据库及分子对接筛选潜在的DPP-IV抑制肽，选择其中四条进行人工合成，验证其DPP-IV抑制活性，通过分子对接分析肽段与DPP-IV分子间相互作用方式，Lineweaver-Burk方法分析肽段抑制模式。选择抑制作用较强的GPQY进行网络药理学分析，预测其对糖尿病的潜在作用机制。采用Swiss Target Prediction和GeneCards数据库挖掘GPQY及糖尿病的作用靶点，String数据库获取蛋白与蛋白互作关系，Cytoscape 3.9.0软件构建PPI网络，DAVID数据库对靶点进行GO与KEGG通路富集分析。结果:筛选验证获得2条DPP-IV抑制GPQY和EACAF，其半抑制浓度（IC₅₀）值分别为348.27±16.11和1024.89±19.67 μmol/L，抑制模式分析表明GPQY为竞争性抑制，EACAF为混合型抑制。分子对接结果显示两条肽段通过氢键、疏水作用和静电作用与DPP-IV结合。由PPI网络筛选到GPQY有STAT3、MMP9、SRC、MAPK1等25个核心作用靶点，KEGG通路富集显示GPQY防治糖尿病通路涉及IL-17信号通路、肿瘤坏死因子（TNF）信号通路、肾素-血管紧张素系统、细胞凋亡等。 结论:驼乳LF是DPP-IV抑制肽的良好来源，由其获得的四肽GPQY可通过多靶点、多通路参与炎症反应，影响细胞增殖分化等多方面防治糖尿病及其并发症。

In Silico Analysis of Novel DPP-IV Inhibitory Peptides Released from Camel Milk Lactoferrin and the Possible Pathways Involved in Diabetes Protection

Objective: To screen novel dipeptidyl peptidase IV (DPP-IV) inhibitory peptides from camel milk lactoferrin (LF) combined with bioinformatics. Network pharmacology was used to explore the potential mechanism of action of screened peptides on diabetes. Methods: Multiple peptides were generated by simulated enzymatic cleavage of lactoferrin using the BIOPEP website. Screening target peptides by combining peptide databases and molecular docking. Four of them were selected for solid-phase synthesis to verify their DPP-IV inhibitory activity. Molecular docking was performed to analyze the interaction between the peptide and DPP-IV molecules, and the Lineweaver-Burk method was used to analyze the inhibition mode of the peptide. Then, GPQY with stronger inhibition was selected for network pharmacological analysis to predict its potential mechanism of action on diabetes. Furthermore, the active targets of GPQY and diabetes were mined from the Swiss Target Prediction and Gene Cards databases, and the String database was used to obtain protein-protein interaction relationships. The PPI networks were built by Cytoscape 3.9.0 software, and the DAVID database was exploited for enrichment analysis of GO and KEGG signaling pathways for key targets. Results: Two DPP-IV inhibitory peptides were obtained with semi-inhibitory concentration (IC₅₀) values of 348.27±16.11 and 1024.89±19.67 μmol/L. Inhibition pattern analysis indicated competitive inhibition of GPQY and mixed-type inhibition of EACAF. Molecular docking results revealed two peptides bound to the active pocket of DPP-IV through hydrogen bonding, hydrophobic interactions and electrostatic interactions. From the PPI network analysis, GPQY had 25 core-acting targets, including STAT3, MMP9, SRC, and MAPK1. The enrichment results were based on KEGG pathways, which showed that GPQY was involved in the IL-17 signaling pathway, tumor necrosis factor (TNF) signaling pathway, renin-angiotensin system, apoptosis, etc. Conclusion: Camel milk lactoferrin is a good source of DPP-IV inhibitor peptide. GPQY could prevent diabetes and its complications through multiple targets and pathways involved in the inflammatory response and cell proliferation and differentiation.