Study on the binding characteristics of hydroxylated polybrominated diphenyl ethers and thyroid transporters using the multispectral technique and computational simulation

Hydroxylated polybrominated diphenyl ethers (OH-PBDEs) are a class of toxic environmental pollutants that are persistent, bioaccumulative, and difficult to degrade. Their structure is very similar to the thyroid hormone (T4) and uses the body’s thyroid transporter (TTR) binding to interfere with the endocrine balance, disrupting the body’s normal physiological activity. According to Fourier transform infrared spectroscopy and dynamics simulation of do_dssp module analysis, there are three kinds of OH-PBDEs that can induce TTR secondary structural changes. Fluorescence spectra and UV–Vis spectra show that for the three kinds of OH-PBDEs for TTR, the main methods of quenching are static quenching and non-radiative energy transfer. According to thermodynamic analysis, ΔG < 0, ΔH > 0, and ΔS > 0 combine to show that the hydrophobic interaction is the main driving force of the combination. From the molecular docking analysis, it was found that 4′-hydroxy-2,2′,4,5′- tetrabromodiphenyl ether (4′-OH-BDE49) and 4 hydroxy-2,2′,3,4′,5,6,6′- heptabromodiphenyl ether (4-OH-BDE188) had a cationic–π interaction with TTR, whereas 4 hydroxy-2,2′,3,4,5,5′,6- heptabromodiphenyl ether (4-OH-BDE187) was bonded to TTR by hydrogen bonds to form stable complexes. In this paper, we highlight the consistency of spectroscopic experiments and computer simulations so as to provide a reliable analytical method for the toxicological properties of small molecule contaminants.