Molecular interaction of human serum albumin with gemini surfactant, 1,6 bis (N,N-hexadecyl dimethyl ammonium) bromide: Influence of micelles and pH

Abstract

The interaction between human seram albumin (HSA) and a cationic gemini (dimeric) surfactant, 1,6 bis (N,N-hexadecyl dimethyl ammonium) bromide (16–6-16) has been investigated. Various analytical techniques, including UV–vis spectroscopy, fluorescence spectroscopy, lifetime fluorescence measurement, circular dichroism (CD), and atomic force microscope (AFM), were employed to investigate these interaction studies. The experiments were conducted in aqueous environments at three distinct pH levels (viz., below (4.0), at (4.7), and above (7.0) the isoelectric point (IP)), as well as both above and below the critical micellar concentration (CMC) of the surfactant (16–6-16). In these experimental conditions, HSA experiences conformational changes, leading to unfolding and denaturation as a result of its interaction with the gemini surfactant molecules (16–6-16). The extent of these conformational changes is found to be associated with both the degree of surfactant partial intercalation and the characteristics (size and charge) of the surfactant aggregates formed. The AFM microscopy studies provide insights into the topographical structural alterations occurring above, at, and below the CMC. Molecular docking analysis further validates the interaction between the protein (HSA) and the gemini surfactant (16–6-16) at a molecular level.