BACKGROUND Many foods contain proteins and polyphenols, but there is a poor understanding of the nature of the inhibitory effect of protein on the biologic activity of polyphenols. The inhibitory mechanism of the food protein lactoferrin on the antibacterial activity of oligomeric ellagitannin oenothein B (OeB) was investigated using fluorescence quenching, isothermal titration calorimetry (ITC), circular dichroism (CD) measurement and molecular docking. RESULTS The antibacterial activity of OeB against S. aureus was inhibited by lactoferrin, which was retained at about 60%. An interaction study revealed that an interaction occurred between OeB and lactoferrin. Thermodynamic analyses indicate that the binding process was spontaneous, and the main driving forces were based on electrostatic interactions that contributed to a high interaction affinity between OeB and lactoferrin. Furthermore, circular dichroism spectra provided insights into conformational changes of lactoferrin. Finally, molecular docking analysis provided a visual representation of a single binding site where OeB interacted with specific amino acid residues located at the active site of lactoferrin. In particular, due to the unique macrocyclic structure and rigid ring structure of OeB, a small number of hydroxyl groups in the rigid structure of OeB interacted with the amino acid of lactoferrin while most of the phenolic hydroxyl groups were not associated with lactoferrin. CONCLUSION Our study provides a theoretical basis for the use of OeB as an antibacterial substance that can be used in nutraceuticals and pharmaceutical products. This article is protected by copyright. All rights reserved.

中文翻译：

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乳铁蛋白对月见草苷 B 抗菌活性的抑制机制：等温滴定量热法和计算对接模拟

背景技术许多食物中含有蛋白质和多酚，但人们对蛋白质对多酚生物活性的抑制作用的性质了解甚少。使用荧光猝灭、等温滴定量热法 (ITC)、圆二色性 (CD) 测量和分子对接研究了食物蛋白乳铁蛋白对低聚鞣花单宁酒苷 B (OeB) 抗菌活性的抑制机制。结果OeB对金黄色葡萄球菌的抗菌活性被乳铁蛋白抑制，保持在60%左右。一项相互作用研究表明，OeB 和乳铁蛋白之间发生了相互作用。热力学分析表明结合过程是自发的，主要驱动力基于静电相互作用，这有助于 OeB 和乳铁蛋白之间的高相互作用亲和力。此外，圆二色光谱提供了对乳铁蛋白构象变化的见解。最后，分子对接分析提供了单个结合位点的可视化表示，其中 OeB 与位于乳铁蛋白活性位点的特定氨基酸残基相互作用。特别是，由于 OeB 独特的大环结构和刚性环结构，OeB 刚性结构中的少量羟基与乳铁蛋白的氨基酸相互作用，而大部分酚羟基与乳铁蛋白无关。结论 我们的研究为 OeB 作为抗菌物质的使用提供了理论基础，该物质可用于营养保健品和医药产品。本文受版权保护。版权所有。