猪去氧胆酸与BSA相互作用研究

目的:采用荧光光谱法研究猪去氧胆酸(HDCA)与牛血清白蛋白(BSA)的相互作用.方法:根据25℃及37℃温度下HDCA对BSA的荧光猝灭作用,通过Stern-volmer方程和Lineweaver-Burk双倒数方程计算反应的猝灭常数和形成常数以判断荧光猝灭类型,采用双对数方程计算HDCA与BSA的结合常数(KA)和结合位点数(n),最后采用热力学公式计算反应前后焓变和熵变确定两者结合的主要作用力类型.结果:HDCA对BSA的荧光淬灭作用属于静态荧光淬灭.在温度25℃和37℃时,HDCA与BSA的结合常数分别为0.258×106 L·mol-1和0.453×104 L·mol-1,结合位点数分别0.92和0.62.由于热力学参数焓变(ΔH=-258.72 KJ·mol-1)和熵变(ΔS=-0.76 J·mol-1·K-1)均小于零,因此确定HDCA与BSA之间的作用力主要为氢键和范德华力作用.结论:HDCA与BSA通过氢键和范德华力形成复合物,经静态猝灭机制引起BSA内源性荧光猝灭.

Study on interaction between hyodesoxycholic acid and bovine serum albumin

Objective： To study the mechanism of interaction of Hyodesoxycholic acid （HDCA） and bovine serum albumin （BSA） by fluorescence spectroscopy. Method： At 25℃ and 37℃, quenching mechanism of the fluorescence of BSA was studied. Steru-volmer equation and Lineweaver-Burk double reciprocal equation were applied to determine the dynamic and static quenching constants. Double logarithmic equation was used to calculate the binding constants （KA） and the number of binding site （n）. Thermodynamic equation was used to discuss the main binding force. Results： fluorescence quenching of BAS by HDCA belongs to static quenching type. At 25 ℃ and 37℃, the binding constants （KA） between HDCA and BSA were 0.258×10^6L·mol^-1 and 0.453×10^4 L·mol^-1, and the binding sites number （n） were 0.92 and 0.62, respectively. According to the thermodynamic parameters, enthalpy change （AH=-258.72 KJ·mol^-1） and entropy change （AS=-0.76 J·mol^-1.K^-1）, the interaction between HDCA and BSA was driven mainly by hydrogen bond and Van der Waals＇ force. Conclusion： HDCA quenches the intrinsic fluorescence of BSA via static quenching mechanism, and the binding is mainly driven by hydrogen bond and Van der Waals＇ force.