Exploring Binding Characteristics of Two Azo Disperse Dyes with Bovine Serum Albumin by Spectroscopic and Molecular Docking Techniques

The interaction between two new synthesized monoazo disperse dyes with bovine serum albumin (BSA) under physiological conditions has been characterized by various spectroscopy and molecular docking techniques. The results showed that A and B dyes could effectively quench the endogenous fluorescence of BSA, formed a 1 : 1 complex with static quenching mechanism for both dyes. The average binding distance (r) between protein and both dyes were calculated by Forster energy transfer measurements and revealed both dyes bind to the BSA residues of tryptophan over short distances. Molecular docking results showed that both monoazo dyes were bound in the hydrophobic cavity of BSA and surrounded by active amino acid residues by forming several hydrogen and van der Waals bonds which changed the microenvironment of amino acid residues of BSA. In addition, molecular docking study indicated that A and B were located within the binding pocket of subdomain IB of BSA. In addition, as shown by the synchronous fluorescence and Fourier transform-infrared spectroscopy, both azo dyes could contribute to the conformational changes of BSA, which could influence its physiological role.