Abstract: The interaction between the mycotoxin aflatoxin G1 (AFG1) and human serum albumin (HSA) was investigated by molecular docking, fluorescence spectroscopy, 3D fluorescence spectrum, and circular dichroism (CD) under simulated physiological conditions (pH 7.4). According to the double logarithmic equation, the major binding mechanism between AFG1 and HSA was a static quenching process. At four different temperatures, the magnitude of binding constants was 104 and the number of binding sites was approximate to 1. Through the molecular docking and the calculation of thermodynamic parameters, the binding site of AFG1 was in the ⅠB hydrophobic cavity, and hydrophobic interaction and hydrogen bonding were the major forces in the binding process. By studying the effect of metal ions on AFG1-HSA reaction, the affinity of AFG1 to HSA could be increased by Mg2+ and Fe3+ but greatly reduced by Zn2+, Mn2+ and Cu2+. The binding distance between AFG1 and HSA was calculated to be 3.26 nm based on Förster’s non-radiation energy transfer theory. The 3D florescence spectra revealed that the microenvironment of amino acid residues became more hydrophobic after the binding reaction. CD spectra revealed that the conformation of HSA was changed during the binding reaction as shown by an increase in α-helix.

Key words: aflatoxin G1 (AFG1), human serum albumin (HSA), spectrum, molecular docking, binding interaction