Molecular dynamics and spectral analysis for the binding of methoxylated polybrominated diphenyl ethers to lysozyme

Abstract The interaction between three methoxylated polybrominated diphenyl ethers (MeO-PBDEs) and lysozyme was investigated using two complementary techniques: computational simulations and multi-spectroscopic methods. Molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) method was used to determine the relative binding energies. Molecular modelling analysis showed van der Waals and hydrogen bonding forces as the major forces responsible for interactions between compounds and Lysozymes. The binding site for 2′-MeO-BDE-3 and 5-MeO-BDE-47 in lysozyme was determined to be at the active pocket, where these ligands bound strongly with lysozyme tryptophan (TRP) residues TRP62, TRP63 and GLU35. In the 3-MeO-BDE-100−lysozyme system, F-shaped and T-shaped interactions between ligand and TRP62 (TRP108) were present, which suggested the stability of the combination. Fluorescence lifetime measurements suggested that be interactions between MeO-PBDEs and lysozyme could be present, and the microenvironment around the TRP residues was slightly altered during the binding process. Circular dichroism (CD) spectroscopy and UV-vis absorption spectra revealed interactions between lysozyme and MeO-PBDEs, thus inducing changes in the lysozyme microenvironment and an increase in its content of α-helix structures.