Interaction of surface active fluorescence probes and bovine serum albumin

The binding between two surface-active substituted 3H-indole fluorescence probes, i.e., iodo-dihexadecyl methyl-2-(p-dodecyl amino phenyl)-3, 3-dimethyl-5-carboethoxy-3H-indole ammonium and iodo-dimethyloctadecyl-2-(p-dodecyl amino phenyl)-3,3-dimethy -5-carboethoxy-3H-indole ammonium, and bovine serum albumin (BSA) in aqueous solution was studied using fluorescence. The binding constant and binding site number of molecule 1 and molecule 2 with BSA were obtained. It was confirmed that electrostatic interaction is the primary driving force for the combination of BSA with molecule 1 or molecule 2. According to the Forster resonance energy transfer theory, the distances between molecule 1, molecule 2 and tryptophan of BSA were calculated to be 2.90 mn and 4.02 nm, respectively.