Comparative study of the interactions between bisphenol analogues and serum albumins by electrospray mass spectrometry and fluorescence spectroscopy

RATIONALE: Bisphenol A and its alternatives are widely used in common consumer products and are known as environmental endocrine disrupting chemicals. Five bisphenol analogues, namely, tetrabromobisphenol A (TBBPA), tetrachlorobisphenol A (TCBPA), 4,4'-sulfonyldiphenol (BPS), bisphenol A (BPA) and 4,4'-hexafluoroisopropylidenediphenol (BPAF), were selected to study their interactions with serum albumins, aiming at a better understanding of the toxicological mechanisms of bisphenol compounds. METHODS: The interactions between human and bovine serum albumins (HSA and BSA) with these five compounds were investigated by electrospray ionization mass spectrometry (ESI-MS). Fluorescence spectroscopy and molecular docking confirmed the ESI-MS observations and provided complementary information with respect to thermodynamic properties and binding modes. RESULTS: TBBPA showed the highest binding ability with HSA and BSA, followed by TBBPA and BPS, whereas BPA and BPAF exhibited little or no binding with these serum albumins. The calculated thermodynamic parameters suggested that hydrogen bonds and electrostatic forces played important roles for these interactions. Binding energies of TBBPA, TCBPA, and BPS calculated by molecular docking were -35.18, -34.39, and -25.89 kJ mol(-1), respectively, in good agreement with ESI-MS measurements. CONCLUSIONS: The results of this study showed that halogenated substituents on the phenolic rings of bisphenol could enhance the binding ability with serum albumins. This work could provide useful information for further research on the relationship between molecular structures and toxicities of bisphenols. Copyright (C) 2016 John Wiley & Sons, Ltd.