Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province, China West Normal University, Nanchong 637002, China.
Mol Biol Rep. 2012 Oct;39(10):9493-508. doi: 10.1007/s11033-012-1814-6. Epub 2012 Jun 26.
This study was designed to examine the interactions of ergosterol with bovine serum albumin (BSA) and human serum albumin (HSA) under physiological conditions with the drug concentrations in the range of 2.99-105.88 μM and the concentration of proteins was fixed at 5.0 μM. The analysis of emission spectra quenching at different temperatures revealed that the quenching mechanism of HSA/BSA by ergosterol was the static quenching. The number of binding sites n and the binding constants K were obtained at various temperatures. The distance r between ergosterol and HSA/BSA was evaluated according to Föster non-radioactive energy transfer theory. The results of synchronous fluorescence, 3D fluorescence, FT-IR, CD and UV-Vis absorption spectra showed that the conformations of HSA/BSA altered in the presence of ergosterol. The thermodynamic parameters, free energy change (ΔG), enthalpy change (ΔH) and entropy change (ΔS) for BSA-ergosterol and HSA-ergosterol systems were calculated by the van't Hoff equation and discussed. Besides, with the aid of three site markers (for example, phenylbutazone, ibuprofen and digitoxin), we have reported that ergosterol primarily binds to the tryptophan residues of BSA/HSA within site I (subdomain II A).
本研究旨在考察麦角甾醇在生理条件下与牛血清白蛋白（BSA）和人血清白蛋白（HSA）的相互作用，药物浓度范围为 2.99-105.88 μM，蛋白质浓度固定在 5.0 μM。不同温度下的发射光谱猝灭分析表明，麦角甾醇对 HSA/BSA 的猝灭机制是静态猝灭。在不同温度下获得了结合位点数 n 和结合常数 K。根据福斯特非放射性能量转移理论，评估了麦角甾醇与 HSA/BSA 之间的距离 r。同步荧光、3D 荧光、FT-IR、CD 和 UV-Vis 吸收光谱的结果表明，在麦角甾醇存在下 HSA/BSA 的构象发生了变化。通过 van't Hoff 方程计算并讨论了 BSA-麦角甾醇和 HSA-麦角甾醇体系的热力学参数，自由能变化（ΔG）、焓变（ΔH）和熵变（ΔS）。此外，借助三个位点标记物（例如，苯丁唑酮、布洛芬和地高辛），我们报告说麦角甾醇主要结合在 BSA/HSA 的色氨酸残基上，位于 I 位点（亚结构域 II A）内。
