俾士麦棕与核酸相互作用的吸收光谱行为

Interaction between Nucleic Acid and Bismarck Brown R by Spectrophotometry

利用分光光度法研究了俾士麦棕与核酸的结合作用.当pH在6.9 ～ 7.6时,体系在446 nm处有最大吸收峰,且在室温下2 min达到稳定且吸光度在3 h之内保持不变.在最佳显色条件下,小牛胸腺脱氧核糖核酸(ct DNA)和鲱鱼脱氧核糖核酸(fs DNA)的线性范围分别为0.1～18 mg/L和0.1～28 mg/L;检出限分别为0.019 mg/L和0.028 mg/L.采用摩尔比法和Rosenthanl作图法测定了俾士麦棕与核酸的结合数,且利用Rosenthanl作图法获得了俾士麦棕与核酸的结合常数.两种方法所得结合数基本一致,即核酸分子中的一个核苷酸可与3个染料分子结合.该方法灵敏度高,稳定性好,操作简便,重现性好以及抗干扰能力强,用于合成样品的分析,回收率在95.2%～102%之间;相对标准偏差低于4.9 %,结果令人满意.

The binding reaction of Bismarck Brown R and nucleic acid was studied by the spectrophotometric method. In the pH ranging from 6.9 to 7.5 the binding reaction was completed within 2 min at room temperature and caused an absorbance increase at 446 nm, and the absorbency remained stable for about 3 h. Under optimum conditions the calibration linearity for calf thymus deoxyribonucleic acid （ct DNA） and fish sperm deoxyribonucleic acid （fs DNA） were linear from 0.1 mg/L to 18 mg/L and 28 mg/L, respectively, and the detection limits were correspondingly 0.019 mg/L and 0. 028 mg/L, Compared with some existing assays, the new method is sensitive, stable, simple, reproducible and relatively free from interference of co-existing species. The analytical results of synthetic samples are satisfactory, with the recoveries of 95.2% - 102% and the relative standard deviations of under 4.9%. In addition, the binding number was estimated by two methods： the molar ratio method and the graphic method of Rosenthanl,and the binding constant K = 9.05× 10^3L/mol was tested by the graphic method of Rosenthanl. The results of the two methods are similar, and every base pair of the nucleic acid can bind three molecules of Bismarck brown R.