Fu Meiling, Zhang Liangliang, Killeen Rick, Onugwu Kenneth E, McCarrick Robert M, Hagerman Ann E
Department of Chemistry & Biochemistry, Miami University, Oxford, OH 45056, USA.
Institute of Advanced Carbon Conversion Technology, Huaqiao University, Xiamen 361021, China.
Molecules. 2025 Jan 15;30(2):320. doi: 10.3390/molecules30020320.
Epigallocatechin gallate (EGCg), an abundant phytochemical in green tea, is an antioxidant that also binds proteins and complex metals. After gastrointestinal absorption, EGCg binds to serum albumin in the hydrophobic pocket between domains IIA and IIIA and overlaps with the Sudlow I site. Serum albumin also has two metal binding sites, a high-affinity N-terminal site (NTS) site that selectively binds Cu(II), and a low-affinity, less selective multi-metal binding site (MBS). We proposed to determine whether EGCg binds or reacts with Cu(II)-serum albumin using fluorescence, UV-Visible and electron paramagnetic resonance (EPR) spectroscopy. Our results suggest that when serum albumin is loaded with Cu(II) in both sites, EGCg binds to the MBS-Cu(II) and reduces the copper to Cu(I). EGCg does not bind to or react with Cu(II) in the high-affinity NTS site. Potential consequences include changes in copper homeostasis and damage from pro-oxidative Fenton reactions.
表没食子儿茶素没食子酸酯（EGCg）是绿茶中一种丰富的植物化学物质，它是一种抗氧化剂，还能结合蛋白质和复合金属。经胃肠道吸收后，EGCg在结构域IIA和IIIA之间的疏水口袋中与血清白蛋白结合，并与Sudlow I位点重叠。血清白蛋白也有两个金属结合位点，一个是选择性结合铜（II）的高亲和力N端位点（NTS），另一个是低亲和力、选择性较低的多金属结合位点（MBS）。我们提议使用荧光、紫外可见光谱和电子顺磁共振（EPR）光谱来确定EGCg是否与铜（II）-血清白蛋白结合或发生反应。我们的结果表明，当血清白蛋白的两个位点都负载有铜（II）时，EGCg与MBS-铜（II）结合，并将铜还原为铜（I）。EGCg不与高亲和力NTS位点的铜（II）结合或发生反应。潜在后果包括铜稳态的变化以及来自促氧化芬顿反应的损伤。
