Multi-spectroscopic and molecular dynamics simulations investigation of the binding mechanism of polybrominated diphenyl ethers to hen egg white lysozyme

摘要

Three PBDEs (BDE25, BDE47, and BDE154) were selected to investigate the interactions between PBDEs and hen egg white lysozyme (HEWL) by molecular modeling, fluorescence spectroscopy, and FT-IR spectra. The docking results showed that hydrogen bonds were formed between BDE25 and residue TRP63 and between BDE47 and TRP63 with bond lengths of 2.178 angstrom and 2.146 angstrom, respectively. The molecular dynamics simulations indicated that van der Waals forces played a predominant role in the binding of three PBDEs to HEWL. The observed fluorescence quenching can be attributed to the formation of complexes between HEWL and PBDEs, and the quenching mechanism is a static quenching. According to Forster's non-radiative energy transfer theory, the binding distances r were < 7 nm, indicating a high probability of energy transfer from HEWL to the three PBDEs. The synchronous fluorescence showed that the emission maximum wavelength of tryptophan (TRP) residues emerged a red-shift. FT-IR spectra indicated that BDE25, BDE47 and BDE154 induced the alpha-helix percentage of HEWL decreased from 32.70% +/- 1.64% to 28.27% +/- 1.41%, 27.50% +/- 1.38% and 29.78% +/- 1.49%, respectively, whereas the percentage of random coil increased from 26.67% +/- 1.33% to 27.60% +/- 1.38%, 29.18% +/- 1.46% and 30.59% +/- 1.53%, respectively.