Fluorescence spectroscopic studies on the interaction of Gemini surfactant 14-6-14 with bovine serum albumin.

The interaction of the cationic Gemini surfactant hexamethylene-1,3-bis (tetradecyldimethylammonium bromide) (14-6-14) with bovine serum albumin (BSA) has been investigated by fluorescence quenching spectra and three-dimensional (3D) fluorescence spectra. The Stern-Volmer quenching constants K(SV) and the corresponding thermodynamic parameters ΔH, ΔG and ΔS have been estimated by the fluorescence quenching method. The results indicated that hydrophobic forces were the predominant intermolecular forces between BSA and the surfactant. Competitive experiments and the number of binding sites calculation show that 14-6-14 can be inserted in site-II (in subdomain IIIA) of BSA. The effect of 14-6-14 on the conformation of BSA was evaluated by synchronous fluorescence spectroscopy and 3D fluorescence spectral methods. The results show that the conformation of BSA was changed dramatically in the presence of 14-6-14, by binding to the Trp and Try residues of BSA. The investigation provides interaction between BSA and 14-6-14 as a model for molecular design and industrial research.