Study of the interaction of gemini surfactant NAE12-4-12 with bovine serum albumin

The interaction of 1,4-bis(3-(dodecyloxylacyl)pyridinium)butane dibromide (designated as NAE12-4-12) and bovine serum albumin (BSA) was investigated by UV–vis absorption, FTIR and fluorescence spectroscopies. The results showed that NAE12-4-12 had strong ability to quench the intrinsic fluorescence of BSA and caused the emission peak blueshift through a static quenching process. The binding constant of NAE12-4-12 with BSA decreased with increasing temperature. The binding process was exothermic, spontaneous and enthalpy driven. The distance between BSA and NAE12-4-12 decreased with incremental concentration of NAE12-4-12. Furthermore, FTIR spectra of BSA–NAE12-4-12 reflected that the secondary structure of BSA changed in the presence of NAE12-4-12, and the curve fitting of IR spectra revealed that the content of α-helix decreased while those of β-sheet, β-turn and random coil rose.