荧光探针法研究铅离子对小牛胸腺DNA构象的影响  

Research on the Influences of Lead Ions on the Conformation of Calf-thymus DNA by Fluorescence Probe Method

作　　者：赵霞[1] 范阔海[1] 

机构地区：[1]山西农业大学临床兽医实验室,山西太谷030801

出　　处：《安徽农业科学》2009年第34期16859-16860,16866,共3页Journal of Anhui Agricultural Sciences

摘　　要：[目的]利用荧光探针法研究铅离子与DNA的作用方式。[方法]采用紫外可见分光光度法检测了DNA的纯度,采用荧光滴定法研究了铅离子对DNA构象的影响。[结果]随着铅离子的加入,DNA-EB复合物的荧光强度逐渐降低。在DNA-EB体系中加入铅离子后,荧光强度随着铅离子浓度的增加而降低,且荧光峰位略有红移。按生物分子的荧光寿命τ0为10ns计算,DNA-EB与铅离子的双分子猝灭常数分别为1.01×1013和4.0×1014L/(mol.s),二者均大于生物分子的最大动态猝灭常数2.0×1010L/(mol.s),说明由铅离子引起的DNA-EB的荧光猝灭属于静态猝灭。根据斜率和外推截距计算出DNA-EB与猝灭剂的解离常数为1.13×10-5mol/L。铅离子与DNA-EB的结合位点为5.56,结合常数为1.51×1029。[结论]铅离子容易与DNA结合,引起DNA构象的变化。[ Objective ] The purpose was to research the action mode of lead ions and DNA by fluorescent probe method. [ Method ] The purity of DNA was detected by UV-vis spectrophotometry and the influence of lead ions on DNA conformation was researched by fluorescence titration. [ Result] The fluorescence intensity of DNA-EB compound was decreased gradually along with the addition of lead ions. After the lead i- ons were added into DNA-EB system, the fluorescence intensity was decreased as the concn, of lead ions was increased and the fluorescent peak-position was a little red shifted. The fluorescence lifetime T0 of biological molecular was 10 ns,it was calculated out according to this that the double-molecular quenching constants of DNA-EB and lead ions were 1.01 × 10^13 and 4.0 × 10^14 L/（ mol · s） resp. , both of them were bigger than the maximum dynamic quenching constant,which was 2.0 × 10^10 L/（ mol ·s） , indicating that the fluorescent quenching induced by lead ions of DNA-EB belong to statistic quenching. According slope and extrapolation intercept, it was calculated out that the dissociation constant of DNA-EB and quencher was 1.13 ×10^-5 mo]/L. The binding site of lead ions on DNA-EB was 5.56 and their binding constant was 1.51× 10^29. [ Conclusion] It was easy for lead ions to combine with DNA and induce the change of DNA conformation.

关 键 词：荧光探针 小牛胸腺DNA DNA构象 

分 类 号：Q5-33[生物学—生物化学]