Binding Interaction of Xanthoxylin with Bovine Serum Albumin

Three independent techniques have been used to investigate the interaction between bovine serum albumin (BSA) and xanthoxylin (XT). UV-Vis absorption spectroscopy measurements showed that there is a XT-BSA complex formed with an overall binding constant of K=1.01×10⁵ L⋅mol⁻¹. Spectroscopic techniques including synchronous fluorescence and Fourier transform infrared (FT-IR) were used to assess the structural effects of XT binding on BSA. The FT-IR experiments showed that there is a decrease of the amount of α-helix from 50.2 to 48.1% and an increase of the β-sheet from 32.9 to 36.9% in the XT-BSA complex. In addition, XT binds to site I of the protein with a distance of 2.07 nm between tryptophan residues and XT.