Interaction of BSA with proflavin: A spectroscopic approach

The interaction of bovine serum albumin (BSA) with proflavin was investigated by spectroscopic tools like absorption and fluorescence spectroscopy as well as laser flash photolysis. Absorption spectroscopy proved the formation of ground-state BSA–proflavin complex. Proflavin was found to quench the intrinsic fluorescence of BSA via static quenching. High value of quenching constant suggested that energy transfer occurred from BSA to proflavin. Distance between the fluorophore in the protein and the ligand (proflavin) was evaluated. Binding constant and number of binding site were determined for proflavin–BSA interaction both in phosphate buffer (pH∼6.8) and in sodium dodecylsulphate media. The values of the thermodynamic parameters suggested that the key interacting forces are van der Waalʹs interaction and hydrogen bonding. Laser flash photolysis study reconfirmed the formation of complex between BSA and proflavin.