Study on the Interaction between Nithophen and Bovine Serum Albumin by Fluorescence Spectrometry

The interaction between nithophen(NP) and bovine serum albumin(BSA) in aqueous solution(Tris-HCl buffer,pH=7.4)was studied by fluorescence spectrometry and UV/Vis spectroscopy.The results showed that the fluorescence quenching of BSA by nithophen was a result of the formation of nithophen-BSA complex,and both static quenching and non-radioactive energy transferring occurred in the fluorescence quenching.The binding constants KA at 298 K,308 K and 318 K were 6.97×104,5.25×104 and 4.96×104 L·mol-1,respectively.And the number of binding sites n were 0.98,0.92 and 0.96,respectively.Based on the thermodynamic parameter analysis,the hydrophobic and electrostatic interaction between NP and BSA was confirmed to be the main binding force.The binding distance r(r=2.19 nm) between nithophen and BSA was obtained according to the Frster theory of non-radioactive energy.Meanwhile,the effect of NP on the conformation of BSA was investigated using synchronous fluorescence spectrometry.The related interaction mechanism was preliminarily proposed.