The binding of scutellarin with human serum albumin (HSA) was investigated at four temperatures, 296,303, 310, and 318 K, by fluorescence, circular dichroism (CD), Fourier transform infrared spectroscopy(FT-IR), and molecular modeling study at pH 7.40. The binding parameters were determined by Scatchard'sprocedure, which are approximately consistent with the results of Stern-Volmer equation. The thermodynamicparameters were calculated according to the dependence of enthalpy change on the temperature as follows:
H is a small negative value (-8.55 kJ/mol), whereas
S is a positive value (65.15 J/mol K). Quenchingof the fluorescence HSA in the presence of scutellarin was observed. Data obtained by fluorescencespectroscopy and CD experiment, FT-IR experiment, and molecular modeling method suggested thatscutellarin can strongly bind to the HSA and the primary binding site of scutellarin is located in site I ofHSA. It is considered that scutellarin binds to site I (subdomain II) mainly by a hydrophobic interaction andthere are hydrogen bond interactions between the scutellarin and the residues Arg222 and Arg257.