The bilateral action between EQ14-2-14 gemini surfactant and bovine serum albumin by DPI and 1H NMR

Gemini surfactant diglycol bis-N-tetradecyl nicotinate dibromide (designed as EQ14-2-14) has been synthesized. The interaction between EQ14-2-14 and bovine serum albumin (BSA) was studied by dual polarization interferometry (DPI), proton nuclear magnetic resonance spectroscopy (1H NMR), Fourier transform infrared spectroscopy (FTIR) and molecular docking. Owing to the binding of EQ14-2-14, the thickness and mass of BSA increased; refractive index (RI) and density firstly raised and then tended to a plateau. In addition, a decrease of α-helix was observed from 54.01% to 31.56% with an increase in random structure from 7.86% to 21.76%. Due to BSA intertwining, the proton resonance signals of EQ14-2-14 shifted up-field and relaxation time decreased with increasing concentration of BSA. The study of molecular docking indicated that EQ14-2-14 embedded into subdomain II of BSA by π-π stacking between the electron-deficit pyridinium rings in EQ14-2-14 and the electron-abundant pyrrole ring in Trp residues of BSA, by hydrogen bonding and by hydrophobic interaction. Therefore the present work offers a whole view of the interaction of BSA with a new gemini surfactant.