The interaction between daidzin and bovine serum albumin (BSA) has been studied with fluorescence spectrum, dynamic light scattering (DLS) under physiological conditions. The experimental results demonstrated that the combination reaction of daidzin with BSA was a static quenching process because of forming a 2∶l complex. And the dominant binding force was hydrophobic interaction. At 310 K, the binding constant and the number of binding sites were 7.4×l04 L•mol－1 and 1.75, respectively. And the conformation of BSA was changed due to the presence of daidzin. Furthermore, the DLS data suggested that aggregation between BSA and daidzin molecules could render the interactions with them. It was also demonstrated that conformation of BSA was changed in daidzin aqueous solution. These provide important information for the study of cardiovascular pharmacological effects of daidzin and the influence of daidzin on the configuration change of BSA.

Key words: laser light scattering, fluorescence spectrum, daidzin, bovine serum albumin, aggregation