Wu Gang-ke, Yan Cheng-nong, Liu Yi
Clinical Laboratory, Central Hospital of Jingzhou, Jingzhou 434020, China.
Guang Pu Xue Yu Guang Pu Fen Xi. 2008 Sep;28(9):2139-43.
Under different temperatures and physiological conditions, with cefuroxime axetil concentrations in the range of 1.959 X 10(-6) to 13.71 X 10(-6) mol x L(-1), and bovine serum albumin (BSA) concentrations at 2.0 X 10(-6) mol x L(-1), the interaction between cefuroxime axetil and BSA was studied by fluorescence spectroscopy, three-dimensional fluorescence spectrum, synchronous fluorescence spectrum and UV-Vis absorption spectroscopy. After analyzing and processing the fluorescence quenching data at different temperatures according to Sterm-Volmer equation, Lineweaver-Burk equation and thermodynamic equation, the average value of the apparent binding constant (K(LB): 3.907 X 10(6) L x mol(-1)), and thermodynamics parameters (enthalpy change delta H: -13.43 kJ x mol(-1), entropy change delta S: 81.90 J x K(-1) and standard Gibbs free energy change delta G0: -38.34 kJ x mol(-1)) were calculated, and the amounts of binding sites (n: 1.042)were measured. The fluorescence quenching mechanism of BSA after cefuroxime axetil was added was discussed. BSA was bound with cefuroxime axetil and formed a new compound. The quenching belonged to static fluorescence quenching. The thermodynamic parameters agree with delta H approximately 0, delta S > 0 and delta G0 < 0, and the binding reaction is mainly entropy-driven and electro-static interaction force plays a major role in the reaction. The maximum emission wavelength of Tyr and Trp had an obvious red shift in the synchronous fluorescence spectra, the fluorescence emission wavelength of two peaks had a blue shift in the three-dimensional fluorescence spectrum of BSA in the presence of cefuroxime axetil and the maximum absorbtion wavelenghs of three systems in the UV-Vis absorption spectra were obviously different. These showed that the changes in the micro-environment of Tyr and Trp and demonstrated that the conformation of BSA changed as cefuroxime axetil had been added. This provides important information for discussing the configuration modification of BSA because of the added cefuroxime axetil, and for elucidating the pharmacological effects of cefuroxime axetil and biological effects in the organism.
在不同温度和生理条件下，头孢呋辛酯浓度范围为1.959×10⁻⁶至13.71×10⁻⁶mol·L⁻¹，牛血清白蛋白（BSA）浓度为2.0×10⁻⁶mol·L⁻¹时，采用荧光光谱法、三维荧光光谱法、同步荧光光谱法和紫外可见吸收光谱法研究了头孢呋辛酯与BSA之间的相互作用。根据Sterm-Volmer方程、Lineweaver-Burk方程和热力学方程对不同温度下的荧光猝灭数据进行分析处理后，计算出表观结合常数的平均值（K(LB)：3.907×10⁶L·mol⁻¹）、热力学参数（焓变ΔH：-13.43kJ·mol⁻¹，熵变ΔS：81.90J·K⁻¹，标准吉布斯自由能变ΔG⁰：-38.34kJ·mol⁻¹），并测定了结合位点数（n：1.042）。探讨了加入头孢呋辛酯后BSA的荧光猝灭机制。BSA与头孢呋辛酯结合形成了一种新化合物。猝灭属于静态荧光猝灭。热力学参数符合ΔH约为0、ΔS＞0和ΔG⁰＜0，结合反应主要由熵驱动，静电相互作用力在反应中起主要作用。在同步荧光光谱中，Tyr和Trp的最大发射波长有明显红移，在头孢呋辛酯存在下BSA的三维荧光光谱中两个峰的荧光发射波长有蓝移，紫外可见吸收光谱中三个体系的最大吸收波长明显不同。这些表明Tyr和Trp微环境发生了变化，证明加入头孢呋辛酯后BSA的构象发生了改变。这为探讨因加入头孢呋辛酯而导致的BSA构象修饰，以及阐明头孢呋辛酯的药理作用和在生物体内的生物学效应提供了重要信息。
