Study on the Interaction between Breviscapinum and Bovine Serum Albumin by Fluorescence Spectrometry

OBJECTIVE To identify the interaction mechanism between breviscapinum and bovine serum albumin(BSA) under the physiological conditions (pH 7.4) by fluorescence spectrometry. METHODS Fixing the concentration of BSA, different concentrations of breviscapinum were added. At excitation wavelength 280 nm, the interaction between breviscapinum and BSA was determined with quenching and synchronous spectrum from 290 nm to 500 nm. RESULTS The fluorescence quenching mechanism between breviscapinum and BSA was static quenching. The binding constants (KA) under 288 K and 310 K between breviscapinum and BSA were 8.295×10⁵ and 3.302×10⁵ L·mol^-1, respectively. The number of binding sites under 288 K and 310 K between breviscapinum and BSA were 1.239 3 and 1.177 0, respectively. According to the thermodynamic parameters, enthalpy change (ΔH) and entropy change (ΔS), which were calculated to be -31.080 kJ·mol^-1 and 5.392 J·mol^-1·K^-1, respectively, the interaction between breviscapinum and BSA was driven mainly by electrostatic interaction. The process of binding was spontaneous because that Gibbs free energy change was negative. Further more, synchronous spectrum was used to investigate the conformational changes of BSA. CONCLUSION In this paper, the interaction mechanism between breviscapinum and BSA was analyzed by fluorescence spectrometry. The results can be applied for the antioxidant new drugs development of breviscapinum.