【摘要】 本文报导了一种对单链DNA灵敏的探针——Tb³⁺研究了Tb³⁺-核酸复合物的荧光光谱及激发光谱,实验结果表明,Tb³⁺与核酸的结合位点主要有两个;核酸上的磷酸部位及鸟嘌呤上的电子供体部位.本文提出了Tb³⁺可作为测定单链DNA及RNA量的一个较灵敏的方法.更多还原

【Abstract】 This Paper reports a sensitive fluorescence probe Tb3+ for single nucleic acid. The fluorescence spectra of Tb3+complexed with GMP, GTP or DNA have three peaks. 488nm,546nm and 580nm, in which 546nm peak is the highest. The fluorescence spectrum and fluorescence excitation spectrum of Tb-GMP has been measured,and the relationship between the fluorescence excitaton spectrum and the absorption spectrum has been discussed.Among the various mononucleotides, Tb3+is more reactive to GMP than others. The fluorescence of Tb-mononucleotides are less than the corresponding triphosphate-nucleotides. The strong fluorescence of Tb3+ was observed when it complexed with native and denatured RNA and denatured DNA. The fluorescence of Tb3+ are linear with fhe contents of RNA(1-14μg/ml) and denatured DNA(0.3-10μg/ml), therefore we propose that it can be used to determine the contents of RNA and single strand DNA, its advantage and disadvantage have been discussed.In researching the effect of pH on the fluorescence of Tb-GMP and Tb-RNA, was observed,it revealed that the fluorescence of Tb3+ quenched below pH 5. It is due to the protonation of N-7 of gaunine which is one of the binding sites of Tb3+ on gaunine. When the competive inhibition of cations were used to measuring Tb3+ - DNA fluorescence, it was observed that 6μm Cu2+could quench the fluorescence of Tb-DNA by 50%,it means that Tb3+ has the same binding site of Cu2+ on DNA. The above experiments illustrate that Tb3+ can bind both the phosphate position and the elec-trindonor of gaunine.In addition, Tb3+ destabling DNA double strand has also been discussed.更多还原