维生素B_5与牛血清白蛋白相互作用的同步荧光光谱和紫外差光谱研究

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

采用荧光光谱和紫外差光谱研究了维生素B5与牛血清白蛋白(BSA)的相互作用;计算了3种温度下B5-BSA体系的结合常数和反应的热力学参数.结果表明,B5对牛血清白蛋白的荧光有猝灭作用,猝灭方式为静态猝灭,结合位点数近似为1;B5-BSA体系的ΔH=-63.90kJ.mol-1,ΔG=-35.29kJ.mol-1,ΔS=-96.02J.K-1.mol-1.据此可知,B5与牛血清白蛋白二者间的主要作用力为氢键、范德华力及质子化等.依据Frster非辐射能量转移理论估算出二者之间的结合距离为1.41nm.此外,同步荧光光谱和紫外差光谱分析结果表明,B5可诱导BSA分子构象变化.

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 △H = -63.90 kJ·mo1-1, △G = 35.29 kJ ·mol -1 , and △S = -96.02 J ·K-1 ·mo1-1 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.