College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035, China.
J Mol Model. 2012 Feb;18(2):493-500. doi: 10.1007/s00894-011-1069-5. Epub 2011 May 4.
The interaction between 8-azaguanine (8-Azan) and bovine serum albumin (BSA) in Tris-HCl buffer solutions at pH 7.4 was investigated by means of fluorescence and ultraviolet-visible (UV-Vis) spectroscopy. At 298 K and 310 K, at a wavelength of excitation (λ (ex)) of 282 nm, the fluorescence intensity decreased significantly with increasing concentrations of 8-Azan. Fluorescence static quenching was observed for BSA, which was attributed to the formation of a complex between 8-Azan and BSA during the binding reaction. This was illuminated further by the UV-Vis absorption spectra and the decomposition of the fluorescence spectra. The thermodynamic parameters ∆G, ∆H, ∆S were calculated. The results showed that the forces acting between 8-Azan and BSA were typical hydrophobic forces, and that the interaction process was spontaneous. The interaction distance r between 8-Azan and BSA, evaluated according to fluorescence resonance energy transfer theory, suggested that there is a high possibility of energy transfer from BSA to 8-Azan. Theoretical investigations based on homology modeling and molecular docking suggested that binding between 8-Azan and BSA is dominated by hydrophilic forces and hydrogen bonding. The theoretical investigations provided a good structural basis to explain the phenomenon of fluorescence quenching between 8-Azan and BSA.
在 pH 7.4 的 Tris-HCl 缓冲溶液中，通过荧光和紫外-可见（UV-Vis）光谱法研究了 8-氮杂鸟嘌呤（8-Azan）与牛血清白蛋白（BSA）之间的相互作用。在 298 K 和 310 K 下，在激发波长（λ（ex））为 282 nm 的条件下，随着 8-Azan 浓度的增加，荧光强度显著降低。BSA 发生了荧光静态猝灭，这归因于在结合反应过程中 8-Azan 和 BSA 之间形成了复合物。这一点通过 UV-Vis 吸收光谱和荧光光谱的分解进一步得到证实。计算了热力学参数 ∆G、∆H 和 ∆S。结果表明，8-Azan 和 BSA 之间的相互作用力是典型的疏水作用力，并且相互作用过程是自发的。根据荧光共振能量转移理论评估的 8-Azan 和 BSA 之间的相互作用距离 r 表明，BSA 向 8-Azan 转移能量的可能性很高。基于同源建模和分子对接的理论研究表明，8-Azan 与 BSA 之间的结合主要由亲水作用力和氢键主导。这些理论研究为解释 8-Azan 与 BSA 之间的荧光猝灭现象提供了良好的结构基础。
