Binding interaction of an anionic amino acid surfactant with bovine serum albumin: physicochemical and spectroscopic investigations combined with molecular docking study

The interaction of a synthesised amino acid surfactant, sodium-N-dodecanoylphenylalaninate (AAS) with a transport protein, bovine serum albumin (BSA) has been uncovered employing various physicochemical and spectroscopic techniques like tensiometry, electro kinetic potential measurements, steady-state fluorometry, time-resolved measurements and circular dichroism (CD) at physiological pH and 298 K. The difference in tensiometric responses of AAS in the absence and presence of BSA indicates a significant interaction operative between them. The zeta (xi) potential measurements have been taken into account in assigning the type of binding interaction between them. The steady-state fluorescence study reveals the sequential unfolding of BSA with stepwise addition of AAS. Stern-Volmer and modified Stern-Volmer plots, Scatchard plots and thermodynamic parameters have been employed to find the type of binding of AAS to BSA. Life-time measurements have been carried out to shed light on the relative amplitude of binding of AAS to the two Trp residues of BSA namely Trp-134 and Trp-213. The changes in protein secondary structure induced by AAS are unveiled by CD measurements. Quantum mechanical calculations involving density functional theory (DFT) and molecular docking analysis have been undertaken to highlight the interactive phenomenon between the two. Thus this work shows a total inspection of an amino acid surfactant-BSA interaction.