In Vitro Study of the Interaction between Ochratoxin A and Human Serum Albumin by Spectroscopic and Molecular Docking Methods

Ochratoxin A (OA) is a mycotoxin that has a potential risk to human health due to its nephrotoxic, immunotoxic and carcinogenic effects. For these reasons the interaction of ochratoxin A with human serum albumin (HSA) was investigated in physiological media by various techniques such as UV-Vis, fluorescence (FL), circular dichroism (CD), attenuated total reflection (ATR), differential scanning calorimetry (DSC), atomic force microscopy (AFM) and molecular docking study via Auto Dock-vina software. The fluorescence intensity of tryptophan in HSA was strongly quenched in the present of OA and the quenching constants and binding constant were valued 108 M-1 and 1.04 M-1, respectively. The CD spectra showed alteration in the secondary structure of HSA in the presence of ochratoxin by reducing the regular alpha helical structure and increasing the beta-sheet structure. By increasing the concentration of OA to 1.25 & mu;M, the intensity of absorption spectrum at 282 nm was increased, indicating the strong interaction of OA and HSA. The enthalpies of these molecular interaction calculated from DSC analysis indicate OA interaction with HAS is exothermic. The docking calculations showed that the amino acids of Lys190, ASP187, LYS519, ARG186 and ARG428 were interacted with OA by hydrogen bonding. The obtained results of this study were found that the presence of OA decreases the alpha-helix structure, increases beta structures (sheets) and irregular structures of protein. Since the second structure of the HSA protein has a close relationship with its biological activities, making changes in the second structure of the protein, by toxin leads to a decrease in the biological activity of the HSA proteinimage