Department of Chemistry, College of Sciences, Northeastern University, Shenyang 110819, PR China; College of Chemistry and Chemical Engineering, Bohai University, Jinzhou 121013, PR China.
College of Chemistry and Chemical Engineering, Bohai University, Jinzhou 121013, PR China.
Spectrochim Acta A Mol Biomol Spectrosc. 2020 Mar 5;228:117771. doi: 10.1016/j.saa.2019.117771. Epub 2019 Nov 11.
To understand the behavior of dimethyl phthalate (DMP) and realize the effect of DMP and its metabolite, monomethyl phthalate (MMP), on the conformation changes of bovine serum albumin (BSA), the interaction mechanisms of DMP and MMP with BSA were investigated by multispectroscopy and molecular docking. The results of the fluorescence quenching experiment showed that the fluorescence quenching of BSA by DMP and MMP was due to the formation of a complex though static quenching, which was also confirmed by time-resolved fluorescence measurements. The binding constants were 8.06 × 10 M and 4.74 × 10 M for DMP-BSA and MMP-BSA, respectively, and the number of binding sites were 1.20 (DMP) and 1.18 (MMP). The thermodynamic parameters showed different binding forces for DMP and MMP with BSA. The binding of DMP to BSA was driven mainly by hydrophobic interactions and hydrogen bonding, and MMP bound to BSA by van der Waals forces and hydrogen bonding, which were in accordance with the results from the molecular docking. The conformation and structural alterations of BSA upon DMP or MMP binding were studied by UV-vis spectroscopy, circular dichroism spectroscopy and synchronous fluorescence spectroscopy. The presence of metabolite did not change the quenching mechanism but decreased the binding affinity of DMP toward BSA as well as shortened the binding distance, which may be attributed to the competition between DMP and MMP for binding to BSA. This study revealed the combined effects of DMP and its metabolite on BSA at the molecular level.
为了了解邻苯二甲酸二甲酯（DMP）的行为，认识 DMP 及其代谢产物邻苯二甲酸单甲酯（MMP）对牛血清白蛋白（BSA）构象变化的影响，通过多光谱和分子对接研究了 DMP 和 MMP 与 BSA 的相互作用机制。荧光猝灭实验结果表明，DMP 和 MMP 对 BSA 的荧光猝灭是由于形成复合物通过静态猝灭，这也通过时间分辨荧光测量得到证实。结合常数分别为 8.06×10^4 M 和 4.74×10^4 M，DMP-BSA 和 MMP-BSA 的结合位点数分别为 1.20（DMP）和 1.18（MMP）。热力学参数表明 DMP 和 MMP 与 BSA 的结合力不同。DMP 与 BSA 的结合主要是由疏水相互作用和氢键驱动的，而 MMP 则通过范德华力和氢键与 BSA 结合，这与分子对接的结果一致。通过紫外可见光谱、圆二色光谱和同步荧光光谱研究了 DMP 或 MMP 结合后 BSA 的构象和结构变化。代谢产物的存在并没有改变猝灭机制，但降低了 DMP 与 BSA 的结合亲和力，也缩短了结合距离，这可能归因于 DMP 和 MMP 与 BSA 竞争结合。本研究在分子水平上揭示了 DMP 及其代谢产物对 BSA 的联合作用。
