Laboratory of Food Process Engineering, Wageningen University & Research, Bornse Weilanden 9, 6708 WG Wageningen, the Netherlands; Institute of Human Nutrition and Food Science, Division of Food Technology, Heinrich-Hecht Platz 10, D-24118 Kiel, Christian-Albrechts-Universität Kiel, Germany.
Otto Diels Institute of Organic Chemistry. Otto-Hahn Platz 4, D-24098 Kiel, Christian-Albrechts-Universität Kiel, Germany.
Food Chem. 2023 Nov 15;426:136496. doi: 10.1016/j.foodchem.2023.136496. Epub 2023 Jun 3.
Non-covalent interactions of phenolics with proteins cannot always be readily identified, often leading to contradictory results described in the literature. This results in uncertainties as to what extent phenolics can be added to protein solutions (for example for bioactivity studies) without affecting the protein structure. Here, we clarify which tea phenolics (epigallocatechin gallate (EGCG), epicatechin and gallic acid) interact with the whey protein β-lactoglobulin by combining various state-of-the-art-methods. STD-NMR revealed that all rings of EGCG can interact with native β-lactoglobulin, indicating multidentate binding, as confirmed by the small angle X-ray scattering experiments. For epicatechin, unspecific interactions were found only at higher protein:epicatechin molar ratios and only with H NMR shift perturbation and FTIR. For gallic acid, none of the methods found evidence for an interaction with β-lactoglobulin. Thus, gallic acid and epicatechin can be added to native BLG, for example as antioxidants without causing modification within wide concentration ranges.
酚类物质与蛋白质的非共价相互作用并不总是能够轻易识别，这往往导致文献中描述的结果相互矛盾。这使得人们不确定在多大程度上可以向蛋白质溶液中添加酚类物质（例如用于生物活性研究）而不影响蛋白质结构。在这里，我们通过结合各种最先进的方法来澄清哪些茶酚类物质（表没食子儿茶素没食子酸酯（EGCG）、表儿茶素和没食子酸）与乳清蛋白β-乳球蛋白相互作用。STD-NMR 表明，EGCG 的所有环都可以与天然β-乳球蛋白相互作用，这表明是多齿结合，这一点得到了小角 X 射线散射实验的证实。对于表儿茶素，仅在较高的蛋白质：表儿茶素摩尔比下，并且仅通过 H NMR 位移干扰和 FTIR 发现其与 β-乳球蛋白具有非特异性相互作用。对于没食子酸，没有一种方法发现其与β-乳球蛋白相互作用的证据。因此，没食子酸和表儿茶素可以添加到天然 BLG 中，例如作为抗氧化剂，而在广泛的浓度范围内不会引起修饰。
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