Center for Research and Innovation, Faculty of Medical Technology, Mahidol University, Nakhonpathom 73170, Thailand.
Center for Data Mining and Biomedical Informatics, Faculty of Medical Technology, Mahidol University, Nakhonpathom 73170, Thailand.
Spectrochim Acta A Mol Biomol Spectrosc. 2019 Jun 5;216:25-34. doi: 10.1016/j.saa.2019.03.004. Epub 2019 Mar 4.
Clioquinol has recently been proposed for the treatment of Alzheimer's disease. It is able to diminish β-amyloid protein aggregation and to restore cognition of Alzheimer's mice. However, its therapeutic benefits for Alzheimer's disease in human remain controversy and need further confirmation. Herein, we have explored the interaction mechanism of clioquinol toward bovine serum albumin (BSA) by means of multi-spectroscopic and docking simulation approaches. Clioquinol interacts with BSA by a combined mechanism of static and dynamic processes. Application of the Hill's equation to fluorescence quenching experiment revealed that the binding constant of the BSA-clioquinol complex is extremely high at 10 M level. Competitive displacement and docking analysis consistently suggested that there are the multiple binding modes of clioquinol toward BSA. Competitive binding study showed that clioquinol shares the binding sites with ibuprofen and digitoxin on albumin, referring to be site II and site III binding compounds. Besides, partial binding in site I was also observed. Docking simulation confirmed that clioquinol favors to bind in site I, site II, site III, fatty acid binding site 5, and the protein cleft between subdomain IB and IIIB of the BSA. Due to its small size and electric dipole property, clioquinol may easily fit in multiple pockets of the BSA. Our finding suggests the potential role of BSA as a clioquinol carrier in the vascular system. Nonetheless, clioquinol-induced BSA aggregation has been observed by the three-dimensional fluorescence technique. This phenomenon may not only impair the BSA, but may also affect other endogenous proteins, which eventually causes adverse effects to human. Therefore, the redesigned or modified molecular structure of clioquinol may reduce its toxicity and improve its bioavailability.
弹性蛋白酶最近被提议用于治疗阿尔茨海默病。它能够减少β-淀粉样蛋白的聚集，并恢复阿尔茨海默病小鼠的认知能力。然而，其在人类阿尔茨海默病中的治疗效果仍存在争议，需要进一步证实。在此，我们通过多光谱和对接模拟方法探讨了弹性蛋白酶与牛血清白蛋白（BSA）的相互作用机制。弹性蛋白酶通过静态和动态过程的综合机制与 BSA 相互作用。应用 Hill 方程对荧光猝灭实验进行分析表明，BSA-弹性蛋白酶复合物的结合常数在 10⁻⁵ M 水平极高。竞争置换和对接分析一致表明，弹性蛋白酶与 BSA 存在多种结合模式。竞争结合研究表明，弹性蛋白酶与布洛芬和地高辛共享白蛋白上的结合位点，指的是结合位点 II 和 III 结合化合物。此外，还观察到部分结合在结合位点 I 上。对接模拟证实，弹性蛋白酶有利于结合在 BSA 的结合位点 I、II、III、脂肪酸结合位点 5 和亚域 IB 和 IIIB 之间的蛋白质裂缝。由于其体积小和偶极性质，弹性蛋白酶可能容易适合 BSA 的多个口袋。我们的发现表明 BSA 作为血管系统中弹性蛋白酶载体的潜在作用。然而，三维荧光技术观察到弹性蛋白酶诱导的 BSA 聚集。这种现象不仅可能损害 BSA，还可能影响其他内源性蛋白质，最终对人体造成不良影响。因此，弹性蛋白酶的重新设计或修饰分子结构可能会降低其毒性并提高其生物利用度。
