Department of Chemistry, Karnatak University, Dharwad 580 003, India.
J Fluoresc. 2011 Mar;21(2):487-95. doi: 10.1007/s10895-010-0735-9. Epub 2010 Oct 6.
The interaction between an anti-inflammatory drug, lornoxicam (LXM) and protein (human serum albumin and bovine serum albumin) was studied by spectroscopic techniques (Fluorescence, synchronous, FT-IR, UV-vis absorption and circular dichroism). The quenching mechanism of fluorescence of the protein by the drug was discussed. Based on the interaction studies carried out at different temperatures by spectrofluorometry, the binding constant and the number of binding sites for drug on protein have been evaluated. The nature of binding force operating between the drug and protein was proposed to be electrostatic and hydrophobic based on thermodynamic parameters. The distance r between the donor (protein) and acceptor (drug) was determined based on the Förster's theory of non-radiation energy transfer and found to be 2.38 nm and 2.56 nm for LXM-BSA and LXM-HSA respectively. Displacement studies with different site probes revealed that the drug bound to the hydrophobic pocket located in sub domain IIA; that is to say, Trp-214 was near or within the binding site. Circular dichroism data of protein in the presence of drug revealed the decreased α-helicity and hence changes in secondary structure of protein. The effects of some common ions were also investigated.
采用荧光光谱、同步荧光光谱、FT-IR 光谱、紫外-可见吸收光谱和圆二色谱等光谱技术研究了抗炎药洛索洛芬（LXM）与蛋白质（人血清白蛋白和牛血清白蛋白）之间的相互作用。讨论了药物对蛋白质荧光的猝灭机制。基于荧光分光光度法在不同温度下进行的相互作用研究，评估了药物与蛋白质结合的结合常数和结合位点数。根据热力学参数，提出药物与蛋白质之间的结合力性质为静电和疏水。基于福斯特非辐射能量转移理论，确定了供体（蛋白质）和受体（药物）之间的距离 r，对于 LXM-BSA 和 LXM-HSA，分别为 2.38nm 和 2.56nm。用不同的位点探针进行的置换研究表明，药物结合在位于亚结构域 IIA 中的疏水口袋中；也就是说，色氨酸 214 靠近或在结合位点内。药物存在时蛋白质的圆二色谱数据显示，α-螺旋减少，因此蛋白质的二级结构发生变化。还研究了一些常见离子的影响。
