Pan Dong-Qi, Jiang Min, Liu Ting-Ting, Wang Qi, Shi Jie-Hua
College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, 310032, China.
State Key Laboratory Breeding Base of Green Chemistry Synthesis Technology, Zhejiang University of Technology, Hangzhou, 310032, China.
Luminescence. 2017 Jun;32(4):481-490. doi: 10.1002/bio.3202. Epub 2016 Aug 23.
The binding interaction between bovine serum albumin (BSA) and enalapril (ENPL) at the imitated physiological conditions (pH = 7.4) was investigated using UV-vis absorption spectroscopy (UV-vis), fluorescence emission spectroscopy (FES), synchronous fluorescence spectroscopy (SFS), Fourier transform infrared spectroscopy (FT-IR), circular dichroism (CD) and molecular docking methods. It can be deduced from the experimental results from the steady-state fluorescence spectroscopic titration that the intrinsic BSA fluorescence quenching mechanism induced by ENPL is static quenching, based on the decrease in the BSA quenching constants in the presence of ENPL with increase in temperature and BSA quenching rates >10 L mol sec . This result indicates that the ENPL-BSA complex is formed through an intermolecular interaction of ENPL with BSA. The main bonding forces for interaction of BSA and ENPL are van der Waal's forces and hydrogen bonding interaction based on negative values of Gibbs free energy change (ΔG ), enthalpic change (ΔH ) and entropic change (ΔS ). The binding of ENPL with BSA is an enthalpy-driven process due to |ΔH°| > |TΔS°| in the binding process. The results of competitive binding experiments and molecular docking confirm that ENPL binds in BSA sub-domain IIA (site I) and results in a slight change in BSA conformation, but BSA still retains its α-helical secondary structure.
采用紫外可见吸收光谱（UV-vis）、荧光发射光谱（FES）、同步荧光光谱（SFS）、傅里叶变换红外光谱（FT-IR）、圆二色光谱（CD）和分子对接方法，研究了在模拟生理条件（pH = 7.4）下牛血清白蛋白（BSA）与依那普利（ENPL）之间的结合相互作用。从稳态荧光光谱滴定的实验结果可以推断，基于在ENPL存在下随着温度升高BSA猝灭常数的降低以及BSA猝灭速率>10 L mol⁻¹ sec⁻¹，ENPL诱导的BSA固有荧光猝灭机制为静态猝灭。该结果表明ENPL-BSA复合物是通过ENPL与BSA的分子间相互作用形成的。基于吉布斯自由能变化（ΔG）、焓变（ΔH）和熵变（ΔS）的负值，BSA与ENPL相互作用的主要结合力是范德华力和氢键相互作用。在结合过程中，由于|ΔH°| > |TΔS°|，ENPL与BSA的结合是一个焓驱动的过程。竞争性结合实验和分子对接的结果证实，ENPL结合在BSA亚结构域IIA（位点I）中，并导致BSA构象略有变化，但BSA仍保留其α-螺旋二级结构。
