【摘要】 采用紫外光谱、荧光光谱、荧光偏振以及K3Fe(CN)6荧光猝灭实验研究了氧氟沙星(Ofloxacin,OFLX)和左氧氟沙星(Levofloxacin,L-OFLX)与小牛胸腺DNA(ctDNA)的相互作用差异性与作用模式。紫外光谱的结果表明,当向OFLX和L-OFLX溶液中加入ctDNA并且浓度增大时,OFLX和L-OFLX的吸收光谱都呈现略微的减色效应,但吸收峰位置没有发生偏移,L-OFLX的减色效应略强于OFLX的减色效应;从荧光光谱以及OFLX和L-OFLX的Scatchard方程,获得其键合常数分别为1.15×105L.mol-1,3.75×105L.mol-1,表明L-OFLX与ctDNA的相互作用要略强于OFLX与ctDNA的相互作用;荧光偏振实验、单双链ctDNA与药物作用实验、K3Fe(CN)6荧光猝灭实验都表明OFLX、L-OFLX与ctDNA的作用模式可能是沟槽结合。更多还原

【Abstract】 The interaction of ofloxacin(OFLX) and levofloxacin(L-OFLX) with calf thymus DNA(ctDNA)was studied by absorption spectra,fluorescence spectra,fluorescence polarization,and K3Fe(CN)6 quenching tests to show the interaction differences and binding modes.The experimental results of absorption spectra indicated that when ctDNA was added to the solution of OFLX or L-OFLX and its concentration was increased,the hypochromic effects in the absorption spectra of OFLX or L-OFLX were observed,and no changes in its maximum absorption wavelengths were found.Fluorescence spectroscopy was an appropriate method to study the interactions between small molecule ligands and biomacromolecule.From the measurements of emission peaks,transfer efficiency of energy,lifetime and so on,a vast amount of information about the interaction will be given.The experimental results indicated that the fluorescence quenching effects of OFLX and L-OFLX were not initiated by the dynamic collision according to the Stern-Volmer equation,and caused by the static quenching of compounds formation.From the Scatchard equation,its association constants were obtained for OFLX and L-OFLX to be 1.15×105 and 3.75×105 L·mol-1,respectively.On the basis of the absorption spectra and the association constants,it was showed that the interaction between L-OFLX and ctDNA was stronger than that of OFLX and ctDNA.There are three modes for the binding of small molecules to DNA double helix: electrostatic binding,groove binding and intercalative binding. The interaction modes between OFLX,L-OFLX and ctDNA were studied by fluorescence polarization,the K3Fe(CN)6 quenching tests and so on.The results showed that the interaction modes of OFLX and L-OFLX with ctDNA were both groove binding.更多还原