Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India.
Eur J Pharm Sci. 2012 Aug 15;46(5):435-45. doi: 10.1016/j.ejps.2012.03.007. Epub 2012 Mar 29.
Understanding physical chemistry underlying drug-protein interactions is essential to devise guidelines for the synthesis of target oriented drugs. Binding of a non-steroidal anti-inflammatory drug, diclofenac sodium (DCF) and an antibiotic drug, cefotaxime sodium (CFT) belonging to the family of cephalosporins with bovine serum albumin (BSA) has been examined using a combination of isothermal titration calorimetry (ITC), differential scanning calorimetry (DSC), steady state and time resolved fluorescence and circular dichroism spectroscopies. Binding affinity of both DCF and CFT with BSA is observed to be of the order of 10(4)M(-1), with the binding profiles fitting well to the single set of binding site model. The disagreement between calorimetric and van't Hoff enthalpies indicates non-adherence to a two-state binding process which could be attributed to changes in the conformation of the protein upon ligand binding as well as with increase in the temperature. Circular dichroism and the fluorescence results, however, do not show any major conformational changes upon binding of these drugs to BSA, and hence the discrepancy could be due to temperature induced conformational changes in the protein. The results of ionic strength dependence and binding in the presence of anionic, cationic and non-ionic surfactants indicate, involvement of more that a single type of interaction in the binding process. The ITC results for the binding of these drugs to BSA in presence of each other indicate that the binding sites for the two drugs are different, and therefore binding of one is not influenced by the other. The DSC results provide quantitative information on the effect of these drugs on the stability of serum albumin. The combined calorimetric and spectroscopic approach has provided a detailed analysis including thermodynamics of the binding of DCF and CFT with BSA qualitatively and quantitatively.
理解药物-蛋白质相互作用的物理化学基础对于设计靶向药物合成的指南至关重要。使用等温滴定量热法（ITC）、差示扫描量热法（DSC）、稳态和时间分辨荧光和圆二色性光谱学，研究了非甾体抗炎药双氯芬酸钠（DCF）和抗生素头孢噻肟钠（CFT）与牛血清白蛋白（BSA）的结合。观察到 DCF 和 CFT 与 BSA 的结合亲和力均为 10（4）M（-1），结合谱与单个结合位点模型拟合良好。量热法和范特霍夫焓值之间的差异表明不符合二态结合过程，这可能归因于配体结合后蛋白质构象的变化以及温度的升高。然而，圆二色性和荧光结果显示，这些药物与 BSA 结合后没有发生任何主要构象变化，因此差异可能是由于蛋白质在温度诱导下发生构象变化所致。离子强度依赖性和在阴离子、阳离子和非离子表面活性剂存在下的结合结果表明，结合过程中涉及不止一种类型的相互作用。在彼此存在的情况下，这些药物与 BSA 结合的 ITC 结果表明，两种药物的结合位点不同，因此一种药物的结合不会受到另一种药物的影响。DSC 结果提供了关于这些药物对血清白蛋白稳定性影响的定量信息。综合量热法和光谱学方法提供了对 DCF 和 CFT 与 BSA 结合的热力学的定性和定量详细分析。
