Study on the interaction between salvianic acid A sodium and bovine serum albumin by spectroscopic methods

The interaction between salvianic acid A sodium (SAS) and bovine serum albumin (BSA) was investigated using fluorescence and ultraviolet spectroscopy at different temperatures under imitated physiological conditions. The experimental results showed that the fluorescence of BSA was quenched by SAS through a static quenching procedure. The binding constants of SAS with BSA were 2.03, 1.17 and 0.71 × 105 L mol−1 at 291, 298 and 305 K, respectively. Negative values of ΔG, ΔH, and ΔS indicate that the interaction between SAS and BSA is driven by hydrogen bonds and van der Waals forces. According to Förster non-radiation energy transfer theory, the binding distance between BSA and SAS was calculated to be about 2.92 nm. The effect of SAS on the conformation of BSA was analyzed using synchronous fluorescence spectroscopy. In addition, the effect of some metal ions Cu2+, Ca2+, Mg2+, and Zn2+ on the binding constant between SAS and BSA was examined.

The interaction between salvianic acid A sodium (SAS) and bovine serum albumin (BSA) was studied by fluorescence and UV–vis spectroscopy. The quenching mechanism, binding constants, thermodynamic parameters, and binding distance were obtained.Figure optionsDownload as PowerPoint slideResearch highlights
► We explored the interaction of BSA and SAS by spectroscopic methods.
► The fluorescence quenching mechanism is static quenching.
► Hydrogen bonds and van der Waals forces were the main force.
► The binding constants, binding sites and thermodynamic parameters were calculated.
► The SAS affects the conformation of tryptophan residues’ microregion.