基于感官评价和分子对接的Pro、Glu二肽与鲜味受体构效关系

The Structure-activity Relationship between Pro-Glu Dipeptides and Umami Receptor Based on Sensory Evaluation and Molecular Docking

摘要:

为探究脯氨酸（Proline，Pro）、谷氨酸（Glutamic Acid，Glu）二肽与鲜味受体分子相互作用，该研究合成了12个Pro、Glu二肽，以感官评价为基础，利用同源建模、分子对接技术研究Pro、Glu二肽与味觉受体第一家族亚型1（Taste Receptor Type 1 Member 1，T1R1）、味觉受体第一家族亚型3（Taste Receptor Type 1 Member 3，T1R3）和钙敏感受体（Calcium Sensitive Receptor，CaSR）的构效关系。结果表明：除脯氨酸-丝氨酸（Proline-serine，Pro-Ser）、缬氨酸-脯氨酸（Valine-proline，Val-Pro）和亮氨酸-谷氨酸（Leucine-glutamic Acid，Leu-Glu）不呈鲜，其余二肽的呈鲜阈值均低于谷氨酸钠阈值（0.3 mg/mL），其中γ-谷氨酸-蛋氨酸（γ-Glutamic Acid-methionine，γ-Glu-Met）和甘氨酸-谷氨酸（Glycine-glutamic Acid，Gly-Glu）的呈鲜阈值最低，为0.07 mg/mL。二肽与T1R1的关键结合位点为Asp147、Thr149、Ser172和Arg277，T1R1是Glu二肽呈鲜的重要受体；与T1R3的关键结合位点为Glu45、Ser147、Val277和His278，Ser147是N-γ-Glu二肽与T1R3受体的关键结合位点；与CaSR的关键结合位点为Leu173、Asn176、Gln179、Arg220、Ser244和Asp275，Glu二肽比Pro二肽更易与CaSR受体结合。二肽与受体主要通过氢键与疏水相互作用结合，呈味较强的二肽在对接时多嵌于受体结合口袋深处；呈味较弱的二肽有的位于结合口袋较浅的位置，有的其疏水区或亲水区暴露于受体表面。该研究有助于阐明鲜味肽与鲜味受体相互作用机制，为深入研究鲜味肽呈鲜机理奠定基础。

Abstract:

Twelve proline (Pro)/glutamic acid (Glu) dipeptides were synthesized to explore the molecular interaction mechanism between Pro/Glu dipeptides and umami receptors. Based on sensory evaluation, the homology modeling and molecular docking technique were used to assess the structure-activity relationship between Pro/Glu dipeptides and umami receptors, including taste receptor type 1 member 1 (T1R1), taste receptor type 3 member 3 (T1R3) and calcium-sensitive receptor (CaSR). Our results indicated that except for proline-serine (Pro-Ser), valine-proline (Val-Pro), and leucine-glutamic acid (Leu-Glu), the umami threshold of other dipeptides was lower than that of sodium glutamate (0.3 mg/mL). The umami threshold of γ-glutamic acid-methionine (γ-Glu-Met) and glycine-glutamic acid (Gly-Glu) was the lowest (0.07 mg/mL). Notably, Asp147, Thr149, Ser172, and Arg277 were the key binding sites of Pro-Glu dipeptides to T1R1, the key umami receptor of Glu dipeptides. Similarly, Glu45, Ser147, Val277, and His278 were the key binding sites to T1R3, whereas Ser147 was the key binding site between N-γ-Glu dipeptides and the T1R3 receptor. Leu173, Asn176, Gln179, Arg220, Ser244, and Asp275 were the key binding sites to CaSR, with Glu dipeptides had a higher affinity for binding to the CaSR receptor compared to Pro dipeptides. Binding of Pro/Glu dipeptides to receptors was mainly achieved through hydrogen bonds and hydrophobic interaction. During molecular docking, dipeptides with strong umami interactions were predominantly embedded in the depth of the receptor binding pocket, whereas dipeptides with weak umami interactions were located in the shallow position of the binding pocket, with some of their hydrophobic or hydrophilic regions being exposed to the surface of the receptors. This study aided in clarifying the interaction mechanism between Pro-Glu dipeptides and umami receptors, establishing a foundation for further study on the mechanism of action of umami peptides.