Probing interaction of bovine serum albumin (BSA) with the biodegradable version of cationic gemini surfactants

Abstract

A multi-technique approach has been used to probe the interaction of model protein bovine serum albumin (BSA) with a series of substantially biodegradable and less cytotoxic ethylene-oxide linked ester-functionalized gemini surfactants (designated as Cm-E2O-Cm, m = 12, 14 and 16). Binding of BSA with the gemini surfactants has been deduced on the basis of steady state fluorescence measurements. Synchronous fluorescence spectra indicate an exposure of the tyrosine residues and entrapment of the tryptophan residues into the hydrophobic cloud of the gemini surfactants. Post surfactant addition, pyrene fluorescence studies depict mild fluctuations in the micropolarity experienced by the probe molecules encapsulated in the protein. Temperature variation fluorescence and UV absorption studies confirm ground state complexation between BSA and the concerned gemini surfactants. Far-UV CD spectra are indicative of slight uncoiling of the alpha helices. These experimental findings are corroborated by the molecular docking results which predict that the probable binding sites for Cm-E2O-Cm gemini surfactants are in the vicinity of aromatic residues. Thus, the investigations presented herein elucidate the binding of serum albumin with surfactants of optimized architecture. Therefore, with further exhaustive screening tests, the Cm-E2O-Cm gemini surfactants may be potentially utilized in pharmaceuticals, cosmetics and other broad application fields.