光谱法研究联二萘酚与牛血清蛋白的相互作用

Study of the interaction of 1,1-binaphthol with bovine serum albumin by spectroscopy

在pH=7.40的Tris-HCl缓冲溶液体系中,利用荧光光谱法、圆二色谱法以及UV-vis吸收光谱法研究了联二萘酚(BINOL)及其两种手性异构体与牛血清蛋白的相互作用。结果表明,BINOL对BSA荧光产生猝灭现象,猝灭方式为静态猝灭。随着温度的升高,BINOL与BSA的结合常数逐渐减小,结合过程是自发且放热的,主要作用力是氢键和范德华力。在相同条件下S-BINOL比R-BINOL更易与BSA结合,其外消旋体的结合能力居于两者之间。根据Forster能量转移理论可知BINOL与BSA的结合距离1.78 nm(S-BINOL-BSA)、1.79nm(Rac-BINOL-BSA)、1.91 nm(R-BINOL-BSA),均小于8 nm。通过对同步荧光光谱法和圆二色谱法发现,BINOL的存在明显改变了BSA的构象,α-螺旋的含量分别由49.45%降到36.34%(R-BINOL-BSA)、57.83%降到34.46%(Rac-BINOL-BSA)、50.16%降到37.81%(S-BINOL-BSA)。

In the pH=7. 40 Tris-HCl buffer solution,the interactions between enantiomers of 1,1-binaphthol（ BINOL） and bovine serum albumin were studied by spectroscopic methods including fluorescence spectroscopy,UV-Visible absorption spectroscopy and CD spectroscopy. The fluorescence of BSA exhibited remarkable decrease upon addition of the BINOL,and the quenching mecha-nism shown to be a static quenching procedure. The binding constant of BINOL with BSA decreased with increasing tempera-ture. The binding reaction was spontaneous and exothermic. The hydrogen bonds and van der Waals force play a main role in the re-action. Under the same condition,the S-BINOL are more likely to combine with BSA than R-BINOL,the binding ability of the Rac-BINOL in between. According to Forster energy transfer theory,the distance r between donor of BSA and acceptor of BINOL are 1. 78 nm（S-BINOL-BSA）,1. 79 nm（Rac-BINOL-BSA）and 1. 91 nm（R-BINOL-BSA）,respectively. All of them are less than 8 nm. Furthermore,CD spectra and synchronous fluorescence spectra results indicated that the conformation of BSA changed in the presence of BINOL,the percentage of α-helix content were decreased from 49. 45%to 36. 34%（ R-BINOL-BSA） ,from 57. 83%to 34. 46%（Rac-BINOL-BSA）and from 50. 16%to 37. 81%（S-BINOL-BSA）.