2'-羟基-2,4-二溴二苯醚与人血清白蛋白作用机制的光谱研究与计算模拟

doi:10.7503/cjcu20141007

摘要/Abstract

摘要：

采用分子对接、分子动力学模拟和光谱法研究了2'-羟基-2,4-二溴二苯醚(2'-OH-BDE-7)与人血清白蛋白(HSA)的相互作用. 同步荧光光谱研究表明, 2'-OH-BDE-7诱导HSA的构象产生变化, 并与分子动力学模拟的结果相吻合. 荧光光谱表明, 2'-OH-BDE-7能引起HSA荧光猝灭, 且其作用机制为静态猝灭和非辐射能量转移. 热力学分析得出ΔG<0, ΔH<0和ΔS<0, 表明氢键和范德华力在HSA-2'-OH-BDE-7的体系中起着重要作用. 竞争实验和分子对接结果表明2'-OH-BDE-7主要结合在HSA的位点Ⅰ. 将计算模拟和光谱实验研究相结合, 为研究小分子和蛋白质相互作用机制提供更多的信息.

关键词: 人血清白蛋白, 2'-羟基-2,4-二溴二苯醚, 荧光光谱法, 分子对接, 分子动力学模拟

Abstract:

The interaction between 2'-hydroxy-2,4-dibromo diphenyl ethers(2'-OH-BDE-7) and human serum albumin(HSA) was investigated with molecular docking, molecular dynamics simulation and spectroscopy techniques. The results of synchronous fluorescence spectroscopy indicated that the conformation of HSA was changed when 2'-OH-BDE-7 binding to HSA, which consistent with the results of molecular dynamics simulations. In addition, the results of fluorescence spectroscopy experiment showed that the intrinsic fluorescence quenching of HSA was reduced by 2'-OH-BDE-7. Static quenching and non-radiation energy transfer are the two main reasons leading to the fluorescence quenching of HSA by 2'-OH-BDE-7. In the process of binding, the entropy, the enthalpy and the Gibbs free energy were negative, which suggested that the interaction between 2'-OH-BDE-7 and HSA was driven mainly by hydrophobic forces and van de Waals forces. Finally, a similar conclusion was obtained from the competitive experiment and molecular docking, which shown 2'-OH-BDE-7 binded human serum albumin at site Ⅰ. Excellent agreement was founded between computer simulations results and spectral experiments to provide more information for the mechanism study on the interaction between 2'-OH-BDE-7 and HSA.

Key words: Human serum albumin, 2'-Hydroxy-2,4-dibromo diphenyl ether(2'-OH-BDE-7), Fluorescence spectrum, Molecular docking, Molecular dynamics simulation

中图分类号:

O641.3

TrendMD:

董露, 易忠胜, 伍智蔚, 王海洋, 张爱茜. 2'-羟基-2,4-二溴二苯醚与人血清白蛋白作用机制的光谱研究与计算模拟. 高等学校化学学报, 2015, 36(3): 516.

DONG Lu, YI Zhongsheng, WU Zhiwei, WANG Haiyang, ZHANG Aiqian. Mechanism Study on the Interaction Between 2'-Hydroxy-2,4-dibromo Diphenyl Ethers and Human Serum Albumin Based on Spectroscopic Methods and Computional Simulations^†. Chem. J. Chinese Universities, 2015, 36(3): 516.

图/表 12

Fig.1 Root-mean-square displacement(RMSD)(A)and root mean square fluctuation(RMSF)(B) of free HSA and 2'-OH -BDE-7-HSA complexes from 10 ns of MD simulations

Fig.2 Rg of free HSA and 2'-OH-BDE-7-HSA complexes structural superposition of HSA at specific time from 10 ns MD MD time/ns: 0(red); 3(purple); 7(blue); 10(green).

Fig.3 Solvent accessible surface areas(SASA) for hydrophobic and hydrophilic moieties in the HSA and 2'-OH -BDE-7-HSA

Fig.4 Synchronous fluorescence spectra of 2'-OH-BDE-7-HSA (A) Δλ=15 nm; (B) Δλ=60 nm. cHSA=1.0 × 10-6 mol/L; 109c2'-OH-BDE-7/(mol·L-1): a—j. 0—9. Left arrow: blue shift; the maximum absorption wavelength move to short wavelength; number value: blue shift value; down arrow: intensity of quenching.

Fig.5 Fluorescence spectra of HSA in the presence of 2'-OH-BDE-7 Inset: Stern-Vomer curves at different temperatures.cHSA=1.0 × 10-6 mol/L; 109c2'-OH-BDE-7/(mol·L-1): a—j. 0—9. Left arrow: blue shift; the maximum absorption wavelength move to short wavelength; number value: blue shift value; down arrow: intensity of quenching.

Table 1 Quenching constant of 2'-OH-BDE-7-HSA interaction at different temperatures

T/K	10⁶K_SV/(L·mol^-1)	10^-14K_q/(L·mol^-1·s^-1)	r
291	4.58	4.58	0.9976
298	3.44	3.44	0.9970
310	2.71	2.71	0.9989

Fig.6 Fluorescence spectrum of HSA(a) and absorbance spectrum of 2'-OH-BDE-7(b) at 298 K cHSA=c2'-OH-BDE-7=1.0 × 10-7 mol/L.

Table 2 Docking results of Surflex-Dock at sites I and Ⅱ

Site	-lgK_d	ΔG/(kJ·mol^-1)	Hydrogen bond
Ⅰ	3.6267	-20.71	Ala291
Ⅱ	3.4474	-19.68

Fig.7 Molecular docking and detailed view of the interactions of 2'-OH-BDE-7 and HSA (A) 2'-OH-BDE-7 located at site Ⅰ of HSA; (B) HSA amino acids residues around 0.5 nm of 2'-OH-BDE-7; (C) electrostatic potential around 2'-OH-BDE-7; (D) combine distance between Trp214 and 2'-OH-BDE-7, r=0.427 nm.

Table 3 Binding constants(Ka), number of binding sites(n) of 2'-OH-BDE-7-HSA system at different temperatures

T/K	10⁷K_a/(L·mol^-1)	n	r
291	2.57	1.11	0.9959
298	1.98	1.11	0.9982
310	0.83	1.07	0.9994

Table 4 Thermodynamic parameters of 2'-OH-BDE-7-HSA system at different temperatures

T/K	ΔH/(kJ·mol^-1)	ΔG/(kJ·mol^-1)	ΔS/(J·mol^-1·K^-1)
291		-41.44
298	-45.79	-41.34	-14.92
310		-41.16

Table 5 Binding constant of experiments of 2'-OH-BDE-7-HSA system(T=298 K)

Compound	2'-OH-BDE-7-HSA	+Ibuprofen	+Warfarin
10⁶K_a/(L·mol^-1)	9.90	9.23	3.67

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