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 K-A and number of binding sites n of IFR with BSA were obtained by fluorescence quenching method. The thermodynamic parameters, enthalpy change (Delta H-theta) and entropy change (Delta S-theta), 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 Forster'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. (c) 2008 Elsevier B.V. All rights reserved.