Application of molecular modelling and spectroscopic approaches for investigating binding of vanillin to human serum albumin

In the present study, the interaction of vanillin and human serum albumin (HSA) has been characterised by molecular modelling, fluorescence, Fourier transform infrared (FT-IR) and circular dichroism (CD) spectroscopic methods. The results of molecular modelling suggested that vanillin was located within the binding pocket of subdomain IIA of HSA mainly by hydrophobic forces. The quenching of HSA fluorescence takes place with a binding constant (K) of 8.8, 7.7, 5.7, 4.2 x 10(4) M-1 at four different temperatures (288, 298, 308, 318 K), respectively. Meanwhile, the number of binding site (n approximate to 1) was also obtained from fluorescence titration data. The enthalpy change Delta H-0 and the entropy change Delta S-0 were calculated to be -20 kJ mol(-1) and 5.8 J mol(-1) K-1 according to the Van't Hoff equation. Furthermore, the alterations of protein secondary structure in the presence of vanillin were explored by FT-IR and CD spectra. (C) 2011 Elsevier Ltd. All rights reserved.