The study of interaction between human serum albumin and alternaria toxins using multi-spectroscopy, molecular docking and molecular dynamic

Alternaria Toxins (ATs) is a kind of mycotoxin widely existed in fruits, vegetables and processed foods. Four ATs including alternariol monomethyl ether (AME), 3 '-hydroxyalternariol monomethyl ether (3HME), altenuisol (ALI) and altenuene (ALT) isolated from Alternaria interacting with human serum albumin (HSA) were studied. The fluorescence quenching method proved that the four ATs and HSA were all statically quenched and formed stable complexes. The binding constant of each AT was calculated after experiment, which were AME: 1.26 x 1013 M- 1s- 1; 3HME: 2.00 x 1013 M- 1s- 1; ALI: 4.43 x 1012 M- 1s- 1 and ALT: 3.64 x 1012 M- 1s- 1 in 298 K, respectively. The interaction force of each AT and HSA was determined by thermodynamic calculation, which shown that the four systems all had van der Waals forces and hydrogen bonds involved in their interaction, but in AME and ALI, electrostatic action was also involved and in 3HME and ALT, hydrophobic action was also involved. It was proved that combination processes were spontaneous heat release process. 3HME and ALT were confirmed to be located at binding site I, wheras the other two were at site II. Synchronous fluorescence, threedimensional (3D) fluorescence, UV absorption and CD spectra were used to investigate the effect of ATs interaction with HSA on the structure and function of HSA. Molecular docking provided a visual understanding and validation of the conclusions, while explaining the preliminary conclusions of the experiment. The root mean square deviation (RMSD), root mean square fluctuation (RMSF), radius of gyration (Rg) were calculated by molecular dynamics simulation.