摘要
以光谱技术和微量热技术相结合的方法研究水溶液中氟罗沙星分子及铁存在时与人血清白蛋白之间结合作用的机制,用荧光淬灭法测得两反应的结合常数分别为K=1.19×l05L.mol-1和1.0565×105L.mo-l1,结合位点数0.97和0.835。依据Fōrster非辐射能量转移机制,得到氟罗沙星与人血清白蛋白间的结合距离(r=3.23nm)。用同步荧光技术考察氟罗沙星对人血清白蛋白构象的影响。微量热法测得氟罗沙星与人血清白蛋白反应的ΔH≈0,ΔS>0,氟罗沙星分子在铁离子存在时与人血清白蛋白反应的ΔH<0,并且ΔS>0表明它们的作用都主要为静电力。由于焓熵互补的作用,两反应的自由能没有发生大的变化。
The binding characteristics of fleroxacin （FLRX） and human serum albumin（HSA） has been studied by fluorescence spectroscopy in aqueous solution, and the interaction influenced by iron （Ⅲ）is also explored in the paper. The results show that the two reaction equilibrium constant and the number of binding sites are K = 1.19×10^5L · mol^-1 ,n =0.97 for FLRX and K = 1. 0565 × 10^5 ,n =0.8355 for FLRX-Fe^3＋ ,respectively. The quenching mechanism of fluorescence of HSA by FLRX is a static quenching procedure. The binding distance between FLRX and HSA and the energy transfer efficiency are obtained based on the theory of Forster spectroscopy energy transfer. The effect of FLRX on the conformation of HSA is also been analyzed by using synchronous fluorescence spectroscopy. The interaction of FLRX and HSA have been studied by flow-mixed microcalorimetry in the absence and presence of iron （Ⅲ）, and their thermodynamic parameters are obtained. The enthalpy change and the entropy change were calculated to be △H≈0, △S 〉 0 in the absence of iron（Ⅲ） ,which indicated that static forces played major role in the interaction of FLRX and HSA,and to be △H 〈 0, △S 〉 0 in the presence of iron（ Ⅲ） ,which indicated that the static forces also played major role in the reaction. The molar free energy, changes of the two reaction is identical each other because the entropy-cnthalpy compensation happened between the two reactions.
出处
《化学研究与应用》
CAS
CSCD
北大核心
2009年第2期184-188,共5页
Chemical Research and Application
基金
福建省青年人才项目(NO:2006F3010)资助
关键词
氟罗沙星
人血清白蛋白
微量热法
荧光法
fleroxacin
human serum albumin
microcalorimetry
fluorescence
