Design, Synthesis, Characterization And Biological Activities Of Artificial Cleavage Agents With Free Radical Oxidative Mechanism

Artificial nuclease can mimic the function of natural nuclease by breaking the backbone of DNA site-specifically. And these small molecules can also be used as molecular biology tools and gene therapy agents. The present dissertation reported the design and synthesis of a series of artificial nuclease with free radical oxidation mechanism, and their DNA binding and DNA cleavage behaviors were also studied by many different experimental methods.In this paper, polyamides which have sequence-specificity to bases were chose as the recognition system and ascorbic acid (Vc) and phenazine di-N-oxide with oxidative mechanism were chose as cleavage system. Two parts above were linked by different flexible linker to form a series of new artificial nucleases. We expected that cleavage ability and sequence-specificity of the cleavage agents were enhanced through the modification of polyamides. The cleavage agents mentioned above were synthesized and characterized. In the process of interaction research between cleavage agents and nucleic acid, gel electrophoresis experiences were performed to analysis the DNA cleavage discrepancy of ascorbic acid molecule in the absence or presence of polyamide. The results showed that DNA cleavage ability of ascorbic acid molecule modified by polyamide (ImPylmPy-γ-Vc) was stronger than that of ascorbic acid (Vc) apparently in the same condition, and it can cleave duplex to form linear DNA through double strand cleavage in the lower concentration. In addition, statistic data suggested that the process of DNA cleavage resulted from ascorbic acid (Vc) is completely random, but that of ascorbic acid (Vc) modified by polyamide (ImPylmPy-γ-Vc) is selectivity and non-random.In the research of binding ability of cleavage agents and DNA, UV spectrum spectrometry was performed to analyze the affinity of cleavage agents in the absence and presence of polyamide to DNA. The data of binding constant, showed that the affinity between ImPyImPy-γ-Vc and DNA increased apparently in the mode of minor groove binding due to the introduction of polyamide.In this paper, another kind of novel cleavage agent phenazine d-N-oxide modified by polyamide was synthesized and characterized.