Study on the interaction of fisetholz with BSA/HSA by multi-spectroscopic, cyclic voltammetric, and molecular docking technique

摘要

The interaction of fisetholz with bovine serum albumin (BSA) and human serum albumin (HSA) was investigated by multi-spectroscopic, cyclic voltammetric, and molecular docking technique. The results revealed that there was a static quenching of BSA/HSA induced by fisetholz. The binding constants (K_a) and binding sites (n) were calculated at different temperatures (293, 303, and 311 K). The enthalpy change (AH) were calculated to be -17.20 kJ mol~(-1) (BSA) and -18.28 kJ mol~(-1) (HSA) and the entropy change (AS) were calculated to be 35.41 J mol~(-1) (BSA) and 24.02J mol~(-1) (HSA), respectively, which indicated that the interaction between fisetholz and BSA/HSA was mainly by electrostatic attraction. Based on displacement experiments using site probes, indomethacin and ibuprofen, the binding site of fisetholz to BSA/HSA was identified as sub-domain IMA, which was further confirmed by molecular docking method. There was little effect of K~+, Ca~(2+), Cu~(2+), Zn~(2+), and Fe~(3+) on fisetholz-BSA or fise-tholz-HSA complex. The spectra of synchronous fluorescence, circular dichroism (CD) and Fourier transform infrared (FT-IR) all showed that fisetholz binding to BSA/HSA leads to secondary structures change of the two serum albumins. According to the Forster non-radiation energy transfer theory, the binding distance between fisetholz and BSA/HSA was 2.94/4.68 nm. The cyclic voltammetry as a supporting tool also indicated that fisetholz interacted with protein.