Probing the molecular mechanism of C.I. Acid red 73 binding to human serum albumin

The molecular mechanism of C.I. Acid red 73 binding to human serum albumin (HSA) was investigated by spectroscopy and molecular docking procedures. The molecular docking results indicated that subdomain IB of HSA was the main active binding site for C.I. Acid red 73. The spectroscopic experiment results showed that the mechanism of the interaction between C.I. Acid red 73 and HSA was dominantly initiated by complex formation and the number of binding site (n) was 1.71 at 298 K. The molecular docking study and thermodynamic analysis suggested that the forces acting was predominantly hydrophobic and hydrogen bond interactions. Far-UV circular dichroism (CD) spectroscopy also revealed that the conformation of the HSA changed slightly after C.I. Acid red 73 bound to the HSA. The mean distance between the bound dye and the Trp residue is 3.28 nm as calculated from Förster energy transfer.