马氏珍珠贝来源DPP-IV抑制活性肽的虚拟筛选及其作用机制

为了快速发现马氏珍珠贝来源二肽基肽酶IV（dipeptidyl peptidase IV，DPP-IV）抑制活性肽，本研究利用数据库中20个已报道的DPP-IV抑制肽组成训练集，构建了药效团模型并通过测试集分子和Fisher随机验证法对模型进行了评估。利用在线网站PeptideCutter，以珍珠贝肉蛋白为原料，进行虚拟酶解。使用最优药效团模型（Hypo1）对虚拟酶解获得的192个低分子肽（氨基酸数小于或等于5）进行初步筛选，接着以分子对接的方法进一步筛选，并且对潜在的DPP-IV抑制活性肽进行固相合成，体外验证其活性并分析其作用机制。结果表明，药效团结合分子对接技术筛选了4个理论上可能具有高活性的DPP-IV抑制肽，即LPIY、VQDR、PIY和APSL。其中，VQDR、PIY没有表现出抑制活性，而LPIY和APSL具有较高的DPP-IV抑制活性，其IC₅₀值分别为521.19 和258.67 μmol/L。与DPP-IV相互作用的机理表明，肽LPIY和APSL与DPP-IV活性口袋中的氨基酸残基形成了多个氢键，且N-端第二个位置的脯氨酸（P）也均与活性口袋中的残基形成了Pi-Alkyl作用，因此促进了LPIY和APSL的DPP-IV抑制作用。本研究为高效筛选珍珠贝来源的DPP-IV抑制肽提供了理论方法。

Virtual Screening and Mechanism of Action of DPP-IV Inhibitory Peptides from Pinctada fucata (P. fucata)

In order to discover the dipeptidyl peptidase IV (DPP-IV) peptides quickly from Pinctada fucata (P. fucata), in this research, 20 reported DPP-IV inhibitory peptides in the database were used to form a training set and construct pharmacophore models, which were then valuated by test set molecules and fisher random validation. The online website PeptideCutter was employed to perform the virtual hydrolysis with P. fucata meat protein as raw materials. The optimal pharmacophore model (Hypo1) was used to initially screen the 192 low-molecular peptides (the number of amino acids was no more than 5), which were obtained by the virtual hydrolysis, and then the molecular docking was performed for further screening. Furthermore, the potential DPP-IV inhibitory peptides were synthesized using a solid-phase method, and their activities were verified in vitro and the interaction mechanism was analyzed. The results showed that 4 potential DPP-IV inhibitory peptides, namely LPIY, VQDR, PIY, and APSL were screened through pharmacophore combined with molecule docking. Among them, VQDR and PIY did not show inhibitory activity, while LPIY and APSL had strong DPP-IV inhibitory activity, with IC₅₀ values of 521.19 and 258.67 μmol/L respectively. The interaction mechanism indicated both peptides formed multiple hydrogen bonds with the amino acid residues within the active pocket of DPP-IV, and the proline (P) at the second position of the N-terminal constructed Pi-Alkyl interactions with the residues of the active pocket, which promoted the DPP-IV inhibitory activity for LPIY and APSL. The current work would provide a theoretical method for screening DPP-IV inhibitory peptides derived from P. fucata efficiently.