In this paper, under the condition of a simulated human physiological environment, steady-state fluorescence, UV spectra, three-dimensional fluorescence, time-resolved fluorescence, and the circular dichroism were implemented to investigate the binding mechanism between bicyclol (BYL) and human serum albumin (HSA). The results revealed a red shift in the UV absorption wavelength of HSA and an increase in absorption intensity of HSA with increasing concentration of bicyclol. Bicyclol quenched the intrinsic fluorescence of HSA via a static quenching mechanism. At 298 K, the number of binding sites (n) and binding constant of BYL–HSA were about 1 and 9.67 × 103 L·mol−1, respectively. The thermodynamic parameters ΔG, ΔH, ΔS are − 22.76 and − 19.07 kJ·mol−1 and 27.17 J·K−1·mol−1 respectively, which demonstrated that the binding of bicyclol and HSA was mainly driven by hydrophobic and electrostatic forces. In addition, the molecular docking method was utilized to further investigate the binding site when BYL is combined with HSA, which indicated that BYL is bound on the hydrophobic cavities of sub-domains IIA and IIIA of HSA, respectively, and that the binding affinity in the IIIA site was much higher than that in the IIA site.

中文翻译：

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多光谱技术和分子对接法探讨双环醇与人血清白蛋白的结合

本文在模拟人体生理环境条件下,利用稳态荧光、紫外光谱、三维荧光、时间分辨荧光和圆二色性研究双环醇(BYL)与人体的结合机制。血清白蛋白 (HSA)。结果表明，随着双环醇浓度的增加，HSA 的紫外吸收波长发生红移，HSA 的吸收强度增加。双环醇通过静态猝灭机制猝灭 HSA 的固有荧光。在 298 K 时，BYL-HSA 的结合位点数 (n) 和结合常数分别约为 1 和 9.67 × 103 L·mol-1。热力学参数ΔG、ΔH、ΔS分别为-22.76和-19.07 kJ·mol-1和27.17 J·K-1·mol-1，这表明双环醇和 HSA 的结合主要是由疏水力和静电力驱动的。此外，利用分子对接方法进一步研究了 BYL 与 HSA 结合时的结合位点，表明 BYL 分别结合在 HSA 的 IIA 和 IIIA 子域的疏水腔上，并且在IIIA 站点远高于 IIA 站点。