光谱法研究洛索洛芬钠与牛血清白蛋白的相互作用及共存金属离子的影响

Study on the interaction between loxoprfen sodium with bovine serum albumin and effect of coexistent metal ion on the reaction by spectroscopic methods

目的研究洛索洛芬钠(LS)和牛血清白蛋白(BSA)的相互作用及共存金属(Mn2+、Cu2+、Cr3+、Mg2+、Fe3+)离子对LS与BSA相互作用的影响。方法在模拟人体生理条件下,用紫外-可见吸收光谱法和荧光光谱法研究LS与BSA的相互作用。298.5、308.5、318.5 K温度下,根据S-V方程计算出猝灭常数(KSV)和速率常数(Kq);根据L-B双倒数方程,计算出静态猝灭结合常数(KLB);根据双对数方程,计算出结合常数(Kb)和结合位点数(n);根据热力学公式,计算出焓变(ΔH)、熵变(ΔS)和吉布斯自由能变(ΔG);根据Hill方程计算出Hill系数(nH)。结果 3个温度下的BSA荧光强度随着LS浓度升高,有规律地降低;KSV、Kq、KLB和nH值随着温度升高而降低;ΔG<0,ΔH<0,ΔS>0;n约等于1;nH小于1。结论 LS对BSA的荧光有猝灭作用,其猝灭过程属于静态猝灭。其相互作用主要靠静电作用力。LS可以被BSA运输,结合位置位于BSA的亚螺旋域ⅡA中,结合位点偏向于酪氨酸。Mg2+、Cu2+、Mn2+和Fe3+对LS与BSA结合产生竞争作用,可提高药效;Cr3+对LS与BSA结合产生促进作用,可减弱药物毒性。

Objective To investigate the interaction between loxoprfen sodium（ LS） and bovine serum albumin（ BSA） and discuss the effect of metal ions（ Mn2 ＋,Cu2 ＋,Cr3 ＋,Mg2 ＋,Fe3 ＋） on the interaction of LS with BSA. The theoretical basis was provided for further research on non-steroidal antiinflammatory drugs and the further study of the inner mechanism and biological effect in organism of LS and the proteins. Methods Under the simulation of the human body physiological conditions,the interaction between LS and BSA was studied with UV-visible absorption spectra and fluorescence spectra. At298. 5,308. 5,318. 5 K,quenching constant（ KSV） and speed constant（ Kq） were calculated by S-V curves. Static quenching constant（ KLB） was obtained by L-B double reciprocal equation. Double logarithmic equation was used to calculate the binding constants（ Kb） and the number of binding site（ n）.Thermodynamic equation was used to obtain ΔH,ΔS,ΔG. Hill＇s coefficients（ nH） was obtained by Hill equation. Results At different three temperatures,with LS concentration increasing,fluorescence intensity of BSA decreased regularly. The value of KSV,Kq,KLBand nHdecreased with the temperature increasing. ΔH and ΔG were lower than 0. ΔS was higher than 0. N was approximately equal to 1 and nH 1. Conclusion The fluorescence of BSA was quenched by LS,which was a static quenching process. The interaction was mainly driven by electrostatic force. LS could be transported by BSA and the binding site was located at sub-domain ⅡA of BSA. The binding site was near by tyrosine residue. Mg2 ＋,Cu2 ＋,Mn2 ＋and Fe3 ＋competed with the interaction of LS with BSA,increasing medical effectiveness. Cr3 ＋promoted on the interaction and reduced toxicology.