Pawar Suma K, Jaldappagari Seetharamappa
Department of Chemistry, Karnatak University, Dharwad 580 003, India.
J Pharm Anal. 2019 Aug;9(4):274-283. doi: 10.1016/j.jpha.2019.03.007. Epub 2019 Mar 16.
Repaglinide (RPG) regulates the amount of glucose by stimulating the pancreas to release insulin in the blood. In view of its biological importance, we have examined the interaction between RPG and a model protein, bovine serum albumin (BSA) employing various spectroscopic, electrochemical and molecular docking methods. Fluorescence spectra of BSA were recorded in the presence and absence of RPG in phosphate buffer of pH 7.4. Fluorescence intensity of BSA was decreased upon the addition of increased concentrations of RPG, indicating the interaction between RPG and BSA. Stern-Volmer quenching analysis results revealed that RPG quenched the intensity of BSA through dynamic quenching mechanism. This was further confirmed from the time-resolved fluorescence measurements. The binding constant as calculated from the spectroscopic and voltammetric results was observed to be in the order of 10 M at 298 K, suggesting the moderate binding affinity between RPG and BSA. Competitive experimental results revealed that the primary binding site for RPG on BSA was site II. Absorption and circular dichroism studies indicated the changes in the secondary structure of BSA upon its interaction with RPG. Molecular simulation studies pointed out that RPG was bound to BSA in the hydrophobic pocket of site II.
瑞格列奈（RPG）通过刺激胰腺在血液中释放胰岛素来调节葡萄糖含量。鉴于其生物学重要性，我们采用各种光谱、电化学和分子对接方法研究了RPG与一种模型蛋白牛血清白蛋白（BSA）之间的相互作用。在pH 7.4的磷酸盐缓冲液中，分别记录了存在和不存在RPG时BSA的荧光光谱。随着RPG浓度的增加，BSA的荧光强度降低，表明RPG与BSA之间存在相互作用。斯特恩-沃尔默猝灭分析结果表明，RPG通过动态猝灭机制猝灭了BSA的荧光强度。时间分辨荧光测量进一步证实了这一点。根据光谱和伏安法结果计算得出的结合常数在298 K时约为10⁶ M，表明RPG与BSA之间具有中等结合亲和力。竞争实验结果表明，RPG在BSA上的主要结合位点是位点II。吸收光谱和圆二色性研究表明，BSA与RPG相互作用后其二级结构发生了变化。分子模拟研究指出，RPG在位点II的疏水口袋中与BSA结合。
