| In recent years, the study of the interaction of DNA with small molecules has been become an important part in the field of chemical biology and clinical medicine. Nucleic acid is not only the fundamental materials of life, but also play an important role in the synthesis of some proteins. In addition, the nucleic acid is the basic unit which constituted organism genetic function and maintained the normal operation of various life functions. And it also plays the decisive role in the series of major biological phenomena. Nucleic acid has a very important role in the practical application, it has found that nearly two thousand genetic diseases have to do with DNA structure. Therefore, the research of the interaction between small molecules and DNA has become an important component of life science, it can be helpful in understanding the pathogenesis of certain diseases and the pharmacological mechanisms of drugs, as well as to provide a favorable information in the molecular structure and efficacy of drug. At the same time, it is also the important basis for guiding the drug designing and drug screening in vitro. In the past period of time, much attention was paid to the binding of small molecules with the DNA. In this assay, we used resonance light scattering method to study the interactions between several different types of small molecules and nucleic acid and discuss the reaction extent and mechanism. The assay is composed of four parts:Part I: The research methods and research status between the small molecules and nucleic acid.We introduced the molecular structure, nature, and the quantitative analysis of nucleic acid, and described the quantitative determination of nucleic acids useing resonance light scattering method in detail. And summarize the research methods and research status between the small molecules and nucleic acid.Part II: Interaction of anticancer drug mitomycin C with nucleic acids analyzed by multi-spectroscopic methodInteractions of the anticancer drug mitomycin C with calf thymus DNA (ctDNA) have been studied by multi-spectroscopic method including resonance light scattering (RLS) technique, ultraviolet spectra (UV) and fluorescence spectra etc. Experiment investigated the optimum conditions of the reaction, the pH, ionic strength and Mitomycin C's concentration have the different effects on the reaction system. And mechanism investigation has shown that mitomycin C can bind to ctDNA by two binding modes: intercalation and groove binding. Mitomycin C binds to DNA through this mixed mode and forms the stable complex, so this interaction destroys the structure of nucleic acids and achieves anti-cancer effect. Part III: Multi-spectroscopic method study the interaction of anti-inflammatory drug ketoprofen and calf thymus DNA and its analytical application.Interactions of the anti-inflammatory drug ketoprofen with calf thymus DNA (ctDNA) in aqueous solution have been studied by multi-spectroscopic method including resonance light scattering (RLS) technique, ultraviolet spectra (UV) and 1H NMR etc. The characteristics of RLS spectra, the effective factors and optimum conditions of the reaction have been unequivocally investigated. Mechanism investigations have shown that ketoprofen can bind to ctDNA by groove binding and form large particles, which resulted in the enhancement of RLS intensity. In Critic acid-Na2HPO4 buffer (pH=6.5), ketoprofen has a maximum peak 451.5nm and the RLS intensity is remarkably enhanced by trace amount of ctDNA due to the interaction between ketoprofen and ctDNA. The enhancement of RLS signal is directly proportional to the concentration of ctDNA in the range 1.20×10-6- 9.88×10-6 mol/L, Based on this, a sensitive and convenient analysis method for the determination of DNA was established. The method is simple, rapid and practical, the correlation coefficient is 0.9989 and detection limit (3σ) is 1.33×10-9 mol/L.Part IV: The synthesis of cobalt complexes and study the interaction with DNA by multi-spectroscopic method.We synthesized a kind of cobalt complex, and speculated the molecular structure of the complex by infrared spectroscopy and elemental analysis. Interactions of the cobalt complexes with calf thymus DNA (ctDNA) have been studied by multi-spectroscopic method including resonance light scattering (RLS) technique, ultraviolet spectra (UV) and fluorescence spectroscopy etc. The results show that cobalt complex can binds to ctDNA forms large particles by electrostatic mode in Tris buffer solution (pH=5.0), which resulted in the enhancement of RLS intensity. The effects of concentration, ionic strength, buffer, pH and foreign substances were discussed in this experiment. The enhancement of RLS signal is directly proportional to the concentration of ctDNA. A new RLS method for determination DNA from 0.05-8.0μg/mL has been developed. This method has high sensitivity and simplicity. The correlation coefficient is 0.9991 and detection limit (3σ) is 4.31ng/mL. |
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