| Under the simulated physiological conditions(at pH 7.4 and ionic strength of 0.15 mol?L-1),the interaction between kaempferide(KF) and bovine serum albumin(BSA) was assessed via fluorescence spectroscopy and ultra-violet absorption spectra under different temperatures,such as 298,304 and 310 K.The binding constant,number of binding sites and binding distance between KF and BSA were analyzed and contrasted by aid of the Tachiya model and Stern-Volmer equation,respectively.The result showed that,for Tachiya model,the binding constant and the binding distance increased with the increase of the temperature,the same as the change trend for Stern-Volmer equation.But the number of binding sites obtained by Tachiya model was much different from that by Stern-Volmer equation.The number of binding sites obtained by Stern-Volmer equation almost had no change with the temperature increasing；To the contrary,the number of binding sites obtained by Tachiya model had a great change with the temperature increasing.The result obtained by Tachiya model corresponds more closely to the practical conditions of interaction between small molecular and biological molecules than that by the Stern-Volmer equation.The thermodynamic parameters were calculated according to the vant Hoff equation.The enthalpy change ΔH,and the entropy change ΔS were found to be 179.87 kJ?mol-1 ,705.61 J?mol-1?K-1,respectively.The thermodynamic results suggest that hydrophobic force plays a major role in stabilizing KF-BSA complex.The effect of KF on the conformation of BSA was also studied by synchronous fluorescence spectra.It indicated that the binding of KF to BSA leads to changes in the conformation of BSA.The interaction between KF and BSA was realized through the combination of KF and tryptophan residue. |