Structural dynamics studies on the binding of aflatoxin B to chicken egg albumin using spectroscopic techniques and molecular docking.

Aflatoxin B, a mycotoxin produced by large number of species including and , has been described as the most potent carcinogenic mycotoxin. In this study, we have used a multiple spectroscopic and molecular docking approach to investigate the interaction of aflatoxin B (AFB) with chicken egg albumin (CEA). Fluorescence spectroscopy, UV-Vis spectroscopy, and three-dimensional fluorescence spectroscopic techniques were employed to gain insight into the conformational changes in CEA in the presence of AFB. Fluorescence spectroscopy revealed ligand-induced quenching in the fluorescence emission spectra of CEA upon binding with AFB. Hyperchromic effect was observed in case of the ground state complex formation between CEA and AFB by UV-Vis spectroscopy. To gain further comprehension into the site of binding of AFB to CEA, competitive site marker displacement assay was performed using warfarin site marker. The magnitude of Δ value calculated from fluorescence-based method was negative which confirmed spontaneous process. The results obtained suggest that the binding is enthalpy driven and van der Waals force and hydrogen bonds are stabilizing the AFB-CEA complex. Three-dimensional fluorescence studies also confirmed the quenching in the fluorescence intensity around tryptophan residues in CEA. Circular dichroism assessment revealed reduction in the alpha helical content of CEA in the presence of AFB. Molecular docking studies showed hydrophobic interaction, van der Waals forces, and hydrogen bonds as major forces present in interaction between CEA and AFB. The overall study confirms conformational and structural alteration in the protein due to binding of AFB.Communicated by Ramaswamy H. Sarma.