Spectroscopic investigation on the interaction of salidroside with bovine serum albumin

This study is designed to examine the interaction of salidroside with bovine serum albumin (BSA) under physiological conditions with drug concentrations in the range of 1.67-20.0 mu M. Spectroscopic analysis of the emission quenching at different temperatures has revealed that the quenching mechanism of salidroside with BSA is static quenching mechanism. The calculated distance r between salidroside and the protein is evaluated according to the theory of Forster energy transfer. The results of FTIR, CD, synchronous fluorescence spectra and UV-vis absorption spectra experiment show that the secondary structures of the protein has been changed in the presence of salidroside. The thermodynamic parameters, enthalpy change (Delta H-0) and entropy change (Delta S-0) are calculated to be -50.50 kJ mol(-1) and -59.13 J mol(-1) K-1 according to van't Hoff equation, which indicate that the hydrogen bonds and van der Waals forces are the intermolecular force stabilizing the complex. The effects of common ions on the binding constants of BSA-salidroside complexes were also investigated. (C) 2008 Elsevier B.V. All rights reserved.