Abstract: The interaction between galangin and bovine serum albumin (BSA) was studied by fluorescence quenching,synchronous fluorescence,three-dimensional fluorescence and circular dichroism spectra.The results suggested that galangin had a strong ability to quench the BSA fluorescence in a static mode.The binding constants (K_a) and site numbers (n) obtained at different temperatures were 9.33×10⁶ L/mol,1.17 (290.15 K);2.34×10⁶ L/mol,1.09 (296.15 K);4.57×10⁵ L/mol,1.01 (303.15 K);1.02×10⁵ L/mol,0.99 (310.15 K),respectively.According to the thermodynamic parameters,hydrogen bond and van Edward force played dominant roles in the interaction between galangin and BSA.While the competitive binding analysis showed that the binding location of galangin to BSA is the Site I of the hydrophobic pocket.Spectra of synchronous fluorescence,threedimensional fluorescence and circular dichroism revealed that galangin interacted with tryptophan residues in BSA more strongly than with tyrosine residues,and the vicinity of tryptophan residues was less hydrophobic.However,conformational changes of α-helix were slighter.

Key words: galangin, bovine serum albumin, synchronous fluorescence spectra, three-dimensional fluorescence spectra, circular dichroism spectra