Study on the Interaction Mechanism of Alpinetin with Bovine Serum Albumin by Fluorescence Spectroscopy

The interaction between alpinetin and bovine serum albumin (BSA) was studied under simulated physiological conditions. Alpinetin quenches the fluorescence of BSA via a static quenching process. The binding affinity and number of binding sites were measured at different temperatures. Effects of Mg2+, Ca2+, Zn2+ and Cu2+ on the binding were also studied. Thermodynamic parameters obtained revealed that electrostatic interaction is the primary force between alpinetin and BSA. According to Frster′s non-radiative energy transfer theory, the distance r0 between alpinetin and BSA found was calculated to be 4.07 nm. The synchronous fluorescence spectra showed the vicinity of tyrosine residue become more hydrophobicity, which no effect was found surrounding the tryptophan residue.