College of Biological and Chemical Engineering, Anhui Polytechnic University, Wuhu 241000, PR China.
College of Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan 250355, PR China.
Bioorg Chem. 2019 Jul;88:102981. doi: 10.1016/j.bioorg.2019.102981. Epub 2019 May 9.
Xanthine oxidase (XO) has emerged as an important target for gout. In our previous study, salvianolic acid C (SAC) was found to show potent XO inhibitory activity, whereas the interaction mechanism was still not clear. Herein, an integrated approach consisting of enzyme kinetics, multi-spectroscopic methods and molecular docking was employed to investigate the interaction between SAC and XO. Consequently, SAC exhibited a rapid and mixed-type inhibition of XO with IC of 5.84 ± 0.18 μM. The fluorescence data confirmed that SAC presented a strong fluorescence quenching effect through a static quenching procedure. The values of enthalpy change, entropy change and Gibbs free energy change indicated that their binding was spontaneous and driven mainly by hydrophobic interactions. Analysis of synchronous fluorescence, circular dichroism and fourier transform infrared spectra demonstrated that SAC induced conformational changes of the enzyme. Besides, further molecular docking revealed that SAC occupied the catalytic center resulting in the inhibition of XO activity. This study provides a comprehensive understanding on the interaction mechanism of SAC on XO.
黄嘌呤氧化酶 (XO) 已成为痛风治疗的一个重要靶点。在我们之前的研究中，发现丹酚酸 C (SAC) 对 XO 具有很强的抑制活性，但相互作用机制尚不清楚。在此，采用包含酶动力学、多种光谱方法和分子对接的综合方法研究了 SAC 与 XO 之间的相互作用。结果表明，SAC 对 XO 表现出快速的混合型抑制作用，IC 为 5.84±0.18 μM。荧光数据证实，SAC 通过静态猝灭过程表现出很强的荧光猝灭效应。焓变、熵变和吉布斯自由能变化的值表明，它们的结合是自发的，主要由疏水相互作用驱动。同步荧光、圆二色性和傅里叶变换红外光谱分析表明，SAC 诱导了酶的构象变化。此外，进一步的分子对接表明，SAC 占据了催化中心，从而抑制了 XO 的活性。这项研究为 SAC 对 XO 的作用机制提供了全面的认识。
