Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, Andhrapradesh 500046, India.
J Phys Chem B. 2010 Mar 4;114(8):3005-12. doi: 10.1021/jp910156k.
N-trans-p-coumaroyltyramine (CT) isolated from Physalis minima is a phenolic substance exhibiting many pharmacological activities like potent inhibition of acetyl cholinesterase, cell proliferation, platelet aggregation, and also antioxidant activity. Here, we have studied the binding of CT with HSA at physiological pH 7.2 by using fluorescence, circular dichroism spectroscopy, mass spectrometry, and molecular docking methods. From the fluorescence emission studies, the number of binding sites and binding constant were calculated to be 2 and (4.5 +/- 0.01) x 10(5) M(-1), respectively. The free energy change was calculated as -7.6 kcal M(-1) at 25 degrees C, which indicates the hydrophobic interactions of CT with HSA and is in well agreement with the computational calculations and molecular docking studies. The changes in the secondary structure of HSA after its complexation with the ligand were studied with CD spectroscopy, which indicated that the protein became partially unfolded. Also, temperature did not affect the HSA-CT complexes. The binding of CT with HSA was detected as 2 molecules bound to HSA was determined using micro TOF-Q mass spectrometry. Further, molecular docking studies revealed that CT was binding at subdomain IIA with hydrophobic interactions and also by hydrogen-bond interactions between the hydroxyl (OH) group of carbon-16 and carbon-2 of CT and Arg222, Ala291, Val293, and Met298 of HSA, with hydrogen-bond distances of 2.488, 2.811, 2.678, and 2.586 A, respectively.
N-反式-对香豆酰基酪胺（CT）是从酸浆果中分离得到的酚类物质，具有许多药理学活性，如强烈抑制乙酰胆碱酯酶、细胞增殖、血小板聚集，以及抗氧化活性。在这里，我们在生理 pH 值 7.2 下使用荧光、圆二色性光谱、质谱和分子对接方法研究了 CT 与 HSA 的结合。从荧光发射研究中，计算出结合位点的数量和结合常数分别为 2 和（4.5 +/- 0.01）x 10(5) M(-1)。在 25°C 时，自由能变化计算为-7.6 kcal M(-1)，这表明 CT 与 HSA 之间存在疏水相互作用，与计算结果和分子对接研究非常吻合。用 CD 光谱研究了配体与蛋白质结合后 HSA 二级结构的变化，表明蛋白质部分展开。此外，温度对 HSA-CT 复合物没有影响。使用微 TOF-Q 质谱检测到 CT 与 HSA 的结合，确定了 2 个配体分子与 HSA 结合。此外，分子对接研究表明，CT 与 HSA 的结合位于亚结构域 IIA 内，通过 CT 的碳-16 上的羟基（OH）基团与碳-2 之间的疏水相互作用以及与 HSA 的 Arg222、Ala291、Val293 和 Met298 之间的氢键相互作用来实现，氢键距离分别为 2.488、2.811、2.678 和 2.586 A。
