Interaction of Caffeine with Bovine Serum Albumin:Determination of Binding Constants and the Binding Site by Spectroscopic Methods

摘要

The interaction of caffeine with bovine serum albumin(BSA)under physiological condition was investigated by fluorescence,UV vis absorption and circular dichroism(CD)spectroscopy.Fluorescence data revealed that the fluorescence quenching of BSA by caffeine was a result of the formation of BSA-caffeine complex.The binding constants Ka at different temperatures and corresponding thermodynamic parameters ΔH,ΔG and ΔS were calculated.The spectroscopic measurements and the thermodynamic parameters suggested that van der Waals interaction and hydrogen bonds were the predominant intermolecular forces to stabilize the complex.The conformational change of BSA induced by caffeine has been analyzed by means of CD and synchronous fluorescence spectroscopy.Furthermore,it is observed from the probe of competitive experiments that the binding location of caffeine with BSA could be the same as warfarin binding site I of BSA,which was also revealed by fluorescence anisotropy.