关键词: 荷叶, 相互作用, 紫云英苷, 牛血清白蛋白, 荧光光谱, 能量转移

Abstract:

The interaction between astragalin (AST) in lotus leaf and bovine serum albumin (BSA) in physiological condition (pH=7.4) was studied by fluorescence spectroscopy and ultraviolet absorption spectroscopy. The results demonstrated that AST could bind to BSA and quenched the intrinsic fluorescence of BSA through static quenching mechanism. The quenching rate constants of biomoleculer, the binding constants, and the number of binding sites between AST and BSA were K_q = 4.31×10¹³ L/mol/s and 3.72×10¹³ L/mol/s, Kd = 2.009×10⁵ L/mol and 0.927×10⁵ L/mol, n = 0.943 and 0.893 at 298 K and 308 K, respectively. According to the free energy change (?G⁰ = -30.25 kJ/mol), the enthalpy change (?H⁰ = -59.02 kJ/mol) and the entropy change（?S⁰ = 96.54 J/mol/K）obtained at 298 K, the binding of BSA to AST was found to be spontaneous and the interaction between BSA and AST was driven mainly by hydrogen bonds and van der Waals forces. In addition, based on the Förster theory of non-radiation energy transfer, the binding distance (r = 4.13 nm) between AST and BSA was close enough to transfer non-radiation energy from BSA to AST.

Key words: lotus leaf, interaction, astragalin, bovine serum albumin, fluorescence spectroscopy, energy transfer