光谱学与光谱分析, 2019, 39 (11): 3614, 网络出版: 2019-12-02
四溴联苯醚(BDE47)与溶菌酶的相互作用研究
Study on the Interaction of Tetra-Brominated Diphenyl Ethers (BDE47) with Lysozyme
四溴联苯醚 溶菌酶 分子模拟 光谱 结合自由能 Tetra-brominated diphenyl ethers Lysozyme Molecular modeling Spectroscopy Binding free energy
摘要
在模拟人体生理条件下, 采用分子模拟结合三维荧光、 圆二色谱、 荧光光谱、 时间分辨荧光等光谱方法, 研究了四溴联苯醚(BDE47)与溶菌酶的相互作用机制。 结果表明: BDE47能有效地猝灭溶菌酶的内源性荧光, 猝灭机制为静态猝灭。 分子对接显示, BDE47与溶菌酶分子中的TRP62, TRP63, ARG61, ASN59, ALA107和ILE98等氨基酸残基具有相互作用, 且BDE47分子中的醚键O原子与TRP63形成了氢键, 氢键距离为2.2 。 三维荧光的实验结果表明, BDE47的加入导致了溶菌酶的荧光强度降低, 峰位置发生略微红移, BDE47与溶菌酶之间的结合作用改变了溶菌酶的微环境。 圆二色谱分析则进一步证明, BDE47的存在引起了溶菌酶的构象发生改变, 导致α-螺旋结构的含量减少。 根据Fster非辐射能量转移理论计算得出, 供体(溶菌酶)与受体(BDE47)的结合距离r为3.31 nm, 满足非辐射能量的条件。 分析四个温度下的热力学参数发现, BDE47与溶菌酶之间的结合是一个自发放热的过程, 主要驱动力为氢键和范德华力, 与分子对接、 结合自由能分析结论一致。
Abstract
The binding of BDE47 to lysozyme was investigated by molecular modeling combined with three-dimensional (3D) fluorescence, circular dichroism (CD) techniques, fluorescence spectroscopy, and time-resolved fluorescence decay under simulative physiological conditions. The results indicated that the quenching reaction of BDE47 to lysozyme was observed, and the quenching mechanism was suggested as static quenching. Molecular docking showed that the amino acid residues, TRP62, TRP63, ARG61, ASN59, ALA107, ILE98 in lysozyme have interactions with BDE47. The hydrogen bonds were formed between the O atom of BDE47 and TRP62 with the distances of 2.2 . The 3D fluorescence experiments showed that the fluorescence intensity of lysozyme gradually decreased in the presence of BDE47 and a red shifted was observed, suggesting that the microenvironment around the TRP-residues of lysozyme has changed during the binding process. Furthermore, CD spectra implied that the interaction of BDE47 with lysozyme induced conformational change of lysozyme, and the content of α-helix structures in lysozyme decreased. The binding distance r between the donor (lysozyme) and acceptor (BDE47) calculated using Frster’s nonradiative energy transfer theory was 3.31 nm, indicating a high probability of energy transfer from lysozyme to BDE47. The thermodynamic parameters at different temperatures indicated that the hydrogen bonds and van der Waals forces played a predominant role in the spontaneous binding process. The results were consistent with the molecular docking and binding free energy analysis.
杨露露, 杨雾, 易忠胜, 赵赛, 段家喜. 四溴联苯醚(BDE47)与溶菌酶的相互作用研究[J]. 光谱学与光谱分析, 2019, 39(11): 3614. YANG Lu-lu, YANG Wu, YI Zhong-sheng, ZHAO Sai, DUAN Jia-xi. Study on the Interaction of Tetra-Brominated Diphenyl Ethers (BDE47) with Lysozyme[J]. Spectroscopy and Spectral Analysis, 2019, 39(11): 3614.