基于分子模拟的鲜味小肽构效关系研究

Umami as one of the five basic tastes, which plays an important role in the culture of traditional Chinese food, is a comprehensive taste with pleasant and appetite-enhancing. Small umami peptides have become a key research in the development of flavor agent base on its characteristics on umami and thickness perception. At present, the research on umami peptides is just in the stage of discovery, and these peptides have not been systematically studied in their characteristics and regularity. In this study, glutamic acid (Glu) or aspartic acid (Asp) in N-terminal amino acid were selected as research targets base on the amino acid sequences of the reported umami peptide, such as Glu-X, Asp-X and Glu-Asp-X (X is arbitrary amino acid). The structures of small peptides were constructed by molecular simulation software (Discovery Studio). The binding models of small peptides with the T1R1/T1R3 receptor were obtained by docking software (Auto Dock), and the key amino acid sites and binding free energy of small peptides with the receptor were preliminarily evaluated. At the same time we will use sensory evaluation standard basing on our previous result and receptor biosensor to test and verify above experiment results, and the relationship equation between the structure characteristics and umami intensity of small peptides was constructed. Thus the umami traits of small peptides will be found, and their structure-activity relationship will also be elucidated. These results will be favor of high-quality flavor agent development.

鲜味是五味之一，令人愉悦并可提高食欲，在我国传统饮食文化中占有十分重要的地位。鲜味小肽是新型鲜味剂研究与开发方向，目前相关研究主要集中在鲜味肽的发掘，其呈鲜特性和呈鲜规律尚未系统研究。本项目拟选择Glu或Asp为N末端氨基酸，以Glu-X、Asp-X和Glu-Asp-X（X为任意氨基酸）组成的2-3肽为研究对象，通过分子模拟软件Discovery Studio构建小肽的三维结构；将小肽分子与前期构建的鲜味受体T1R1/T1R3模型通过软件Auto Dock对接，并对结合模型优化；分析不同小肽与受体的结合区域和关键氨基酸位点，计算小肽与受体的结合自由能以表征它们的结合强度，开展小肽的鲜味评价；利用前期建立的鲜味评价公式对小肽鲜度定量，受体生物传感器测定小肽激活常数，以验证小肽鲜味，建立鲜味小肽结构特征与呈鲜强度的关系。本项目探明鲜味小肽的呈鲜规律及其构效关系，为开发高效鲜味剂提供理论支撑。

鲜味作为第五种基本滋味，令人愉悦并可提高食欲。当前，具有营养和呈味双重特性的鲜味肽是新型鲜味剂研究与开发的主要方向。本项目以鲜味肽为研究对象，构建了滋味（鲜味肽）数据库TastePeptidesDB；揭示了鲜味小肽关键呈鲜的物理化学性质、分子指纹结构等指标，基于分子描述符、共接触对接、分子指纹和集成算法建立了鲜味肽的筛选模型；解析了鲜味肽与鲜味受体T1R1/T1R3关键结合位点并进一步阐述鲜肽小肽中D/E呈鲜效应规律。研究结果表明：数据库TastePeptidesDB支持滋味肽数据查询、下载和上传；鲜味肽的溶解度、电荷和范德华半径（vdwr）和分子量是鲜味判别的重要特征且D/E氨基酸的位置/数量也是重要的判断信息；Morgan598、322、952在鲜味模型中都是最重要的分子指纹，其次是Morgan148、322、428、509、598、650、805等；在鲜味模型TPDM的准确率可达0.90，准确度、召回率、精准度、AUC、马修斯系数等指标中与其他同类服务器模型相比都表现出最佳的性能；鲜味肽与受体的主要相互作用为氢键作用、疏水作用和π堆积作用，其中T1R1是主要的鲜味识别蛋白，关键残基为151R、153R、154T、157A、158L、161P；按照搭配效应原则添加D/E氨基酸可以有效改善肽的鲜味效果，降低识别阈值。综上，鲜味小肽呈鲜规律的解析，可进一步促进高效鲜味肽类工业化制备以拓展其在食品工业中的应用。