Lu Jian-Quan, Jin Fen, Sun Ting-Quan, Zhou Xing-Wang
Hubei Key Laboratory of Bioanalytical Technique, Hubei Normal University, Huangshi 435002, China.
Int J Biol Macromol. 2007 Mar 10;40(4):299-304. doi: 10.1016/j.ijbiomac.2006.08.010. Epub 2006 Oct 9.
The binding reactions of lomefloxacin-copper(II) complex (LMF-Cu) or LMF to bovine serum albumin (BSA) in physiological solution were investigated by multi-spectroscopy. The binding constant, the number of binding sites and the binding distance between LMF-Cu or LMF and BSA were obtained by a fluorescence quenching method and according to the mechanism of Forster-type dipole-dipole non-radioactive energy-transfer, respectively. Enthalpy and entropy changes for two systems were calculated to be -7.970 kJ mol(-1) and 47.438 J mol(-1)K(-1) for LMF-BSA, -12.469 kJ mol(-1) and 33.542 J mol(-1)K(-1) for LMF-Cu-BSA, respectively. The highly positive values observed for the entropy give evidence for a strong interaction. The values of DeltaH and DeltaS in two systems are similar, indicating that electrostatic interactions in two systems play major role. The effect of LMF-Cu or LMF on the conformation of BSA was also analyzed by synchronous fluorescence, three-dimensional fluorescence and circular dichroism spectra. The results showed that the presence of Cu ion in LMF-Cu can affect the conformation of BSA to some degree. All the results revealed that the addition of copper ion promotes the interaction of lomefloxacin with bovine serum albumin.
采用多种光谱法研究了生理溶液中洛美沙星 - 铜（II）配合物（LMF - Cu）或洛美沙星（LMF）与牛血清白蛋白（BSA）的结合反应。分别通过荧光猝灭法并根据福斯特型偶极 - 偶极非辐射能量转移机制，获得了LMF - Cu或LMF与BSA之间的结合常数、结合位点数和结合距离。计算得出两个体系的焓变和熵变，LMF - BSA体系分别为 - 7.970 kJ·mol⁻¹和47.438 J·mol⁻¹·K⁻¹，LMF - Cu - BSA体系分别为 - 12.469 kJ·mol⁻¹和33.542 J·mol⁻¹·K⁻¹。观察到的熵的高度正值证明了存在强相互作用。两个体系中ΔH和ΔS的值相似，表明两个体系中的静电相互作用起主要作用。还通过同步荧光、三维荧光和圆二色光谱分析了LMF - Cu或LMF对BSA构象的影响。结果表明，LMF - Cu中铜离子的存在会在一定程度上影响BSA的构象。所有结果表明，铜离子的加入促进了洛美沙星与牛血清白蛋白的相互作用。
