Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh, India.
J Biomol Struct Dyn. 2023 Apr;41(7):2630-2644. doi: 10.1080/07391102.2022.2036238. Epub 2022 Feb 9.
Esculin is structurally a hydroxycoumarin found in various medicinal plants. This study investigates the binding mode of esculin with bovine serum albumin by employing numerous spectroscopic studies and molecular docking approaches. Ultraviolet absorption spectroscopy revealed ground state complex formation between esculin and bovine serum albumin. At the same time, steady-state fluorescence studies showed quenching in the fluorescence emission spectra of BSA in the presence of esculin. To get insight into the location of the binding pocket of esculin on BSA, warfarin and ibuprofen site markers were used. Competitive site marker displacement assay revealed that esculin binds to Sudlow's site I (subdomain IIA) in bovine serum albumin. Thermodynamic parameters suggested that hydrogen bonding and van der Waals interaction stabilizes the esculin-BSA complex. Förster's non-radiation energy transfer analysis described the high propensity of energy transfer between bovine serum albumin and esculin. The molecular docking approach facilitated locating the binding pocket, amino acid residues involved, types of interacting forces, and binding energy (ΔG) between esculin and BSA. Circular dichroism revealed the effect of the binding of esculin on the secondary structure and helped understand the thermal unfolding profile of BSA in the presence of esculin.Communicated by Ramaswamy H. Sarm.
秦皮素在结构上是一种羟基香豆素，存在于多种药用植物中。本研究通过多种光谱研究和分子对接方法研究了秦皮素与牛血清白蛋白的结合模式。紫外吸收光谱表明秦皮素与牛血清白蛋白在基态下形成复合物。同时，稳态荧光研究表明秦皮素的存在会猝灭 BSA 的荧光发射光谱。为了深入了解秦皮素在 BSA 上的结合口袋位置，使用了华法林和布洛芬作为位点标记物。竞争位点标记物置换实验表明，秦皮素结合到牛血清白蛋白的 Sudlow 位点 I（亚域 IIA）。热力学参数表明，氢键和范德华相互作用稳定了秦皮素-BSA 复合物。福斯特非辐射能量转移分析描述了 BSA 与秦皮素之间能量转移的高倾向。分子对接方法有助于定位结合口袋、涉及的氨基酸残基、相互作用力的类型和秦皮素与 BSA 之间的结合能（ΔG）。圆二色性揭示了秦皮素结合对 BSA 二级结构的影响，并有助于了解秦皮素存在时 BSA 的热变性轮廓。由 Ramaswamy H. Sarm 交流。
