Institute of Chemical Industry of Forest Products, CAF, Nanjing 210042, China; Key Lab. of Biomass Energy and Material, Nanjing, Jiangsu Province 210042, China; Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing 210042, China.
Institute of Chemical Industry of Forest Products, CAF, Nanjing 210042, China; Key Lab. of Biomass Energy and Material, Nanjing, Jiangsu Province 210042, China; Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing 210042, China.
Food Chem. 2019 Dec 15;301:125294. doi: 10.1016/j.foodchem.2019.125294. Epub 2019 Jul 29.
The interaction of copper complexed with (-)-epigallocatechin-3-gallate (EGCG) and bovine serum albumin (BSA) was investigated using fluorescence, circular dichroism (CD) spectroscopy, HPLC and protein-ligand docking. The fluorescence quenching efficiency of BSA by EGCG was enhanced after EGCG was complexed with copper, and the EGCG-Cu complex exhibited a higher apparent binding affinity (8.88 × 10 M) to BSA compared with EGCG alone (5.17 × 10 M). The CD experiment showed that both the EGCG-BSA and [EGCG-Cu]-BSA interactions resulted in the unfolding of the secondary structure of the protein. Results of competitive binding experiments confirmed that the location of EGCG and EGCG-Cu complex binding in BSA was site I. Furthermore, molecular modeling was used to identify the amino acid residue in site I and site II that play key roles in this binding interaction. The data suggest that most of the residues involved in the [EGCG-Cu]-BSA reaction belong to the subdomains IIa (site I) of BSA.
采用荧光光谱法、圆二色光谱法（CD）、高效液相色谱法和蛋白配体对接技术研究了铜配合物与（-）-表没食子儿茶素-3-没食子酸酯（EGCG）和牛血清白蛋白（BSA）的相互作用。EGCG 与铜形成配合物后，增强了 EGCG 对 BSA 的荧光猝灭效率，并且 EGCG-Cu 配合物与 BSA 的表观结合亲和力（8.88×10M）高于 EGCG 单独与 BSA 的结合亲和力（5.17×10M）。CD 实验表明，EGCG-BSA 和 [EGCG-Cu]-BSA 相互作用均导致蛋白质二级结构的展开。竞争结合实验的结果证实，EGCG 和 EGCG-Cu 配合物在 BSA 中的结合位置是 I 型结合位点。此外，分子建模用于鉴定 I 型和 II 型结合位点中与结合相互作用相关的关键氨基酸残基。数据表明，[EGCG-Cu]-BSA 反应涉及的大多数残基属于 BSA 的 IIa 亚结构域（I 型结合位点）。
