Mechanism evaluation of the interactions between bisphenol AP and bovine serum albumin based on multi-spectroscopy, wavefunction analysis, and molecular docking

The hazardous effects of bisphenol compounds on organisms have attracted wide attention. Hence, elaborating of the specific binding mode of emerging contaminants to macromolecules provides a pivotal insight into the interaction mechanism. In the present study, the structure changes of bovine serum albumin (BSA) upon binding with bisphenol AP (BPAP) were explored via multi-spectroscopies under simulated physiological conditions. Stern-Volmer calculation showed BPAP quenched the endogenous fluorescence of BSA by static quenching. Thermodynamic results with respect to temperatures indicate that the van der Waals force and hydrogen bond interactions play a pivotal role in BSA-BPAP complex formation. Circular dichroism and Fourier transform infrared spectroscopies also quantitatively confirm the secondary structural changes of the complex. Explicit topological analysis was theoretically conducted by the wavefunction analysis method. Electrostatic potential map pinpointed the global surface minimum and maximum of BPAP, which correspond to −26.86 and 52.50 kcal mol −1 around oxygen atom and hydrogen atom, respectively. To acquire clearer perspective, local orbital localizer and electron localization function were calculated to visually represent the electron delocalization in BPAP. More specifically, molecular docking indicated that BPAP was located in the hydrophobic cavity of BSA. Herein, the experimental and theoretical results reveal BPAP and BSA interaction mechanism in detail. These insights have great value in warning the toxicity assessment of BPAP on BSA in humans and wildlife.