Interaction of the irisflorentin with bovine serum albumin: A fluorescence quenching study

The interaction between irisflorentin (IFR) and bovine serum albumin (BSA) in physiological buffer (pH = 7.4) was investigated by fluorescence quenching technique and UV/vis absorption spectroscopy. The results of fluorescence titration revealed that IFR could strongly quench the intrinsic fluorescence of BSA through a dynamic quenching procedure. The apparent binding constants KA and number of binding sites n of IFR with BSA were obtained by fluorescence quenching method. The thermodynamic parameters, enthalpy change (ΔHθ) and entropy change (ΔSθ), were calculated to be 18.45 kJ mol−1 >0 and 149.72 J mol−1 K−1 >0, respectively, which indicated that the interaction of IFR with BSA was driven mainly by hydrophobic forces. The process of binding was a spontaneous process in which Gibbs free energy change was negative. The distance r between donor (BSA) and acceptor (IFR) was calculated to be 3.88 nm based on Förster’s non-radiative energy transfer theory. The results of synchronous fluorescence spectra showed that binding of IFR with BSA can induce conformational changes in BSA.