Study on interaction of vitamin B_5 with bovine serum albumin by synchronous fluorescence spectrometry and ultraviolet difference spectrometry

The interaction of B5 with bovine serum albumin(BSA) was investigated by fluorescence spectrometry and ultraviolet(UV) difference spectrometry under simulative physiological conditions.The binding constants and thermodynamic parameters of B5-BSA at different temperatures were calculated.Results indicate that B5 can quench the fluorescence of BSA via a static quenching route,and the binding site value of the B5-BSA system is about 1.Besides,B5-BSA system has thermodynamic parameters of ΔH =-63.90 kJ · mol-1,ΔG =-35.29 kJ · mol-1,and ΔS =-96.02 J · K-1 · mol-1 at three different temperatures.This means that hydrogen bonding and van der Waals interactions as well as protonation play an important role in stabilizing the B5-BSA complex.Moreover,the distance between the acceptor(B5) and donor(BSA),estimated based on fluorescence resonance energy transfer theory,is 1.41 nm,while synchronous fluorescence spectra and UV difference spectra demonstrate that B5 is able to induce the conformation variation of BSA.