Intrinsic Reactivity of DNA Secondary Structure

NA二级结构的准确描述现在必须 包括许多构象，而不是由 无规卷曲或沃森-克里克双螺旋。 结构 变体如十字形、发夹和铰链DNA沿着 随着更短暂地形成隆起或滑动序列 经常被认为是基因突变的可能来源 热点 这种异常构象可能会对 DNA修复的保真度和核苷酸的速率 改性 本研究旨在研究 分子基础的这后一个过程，系统地 评价双链体结构对反应性的影响 在一个定义良好的模型系统中。 合成寡核苷酸的光化学修饰 作为衍生化的主要方法， 具体地，嘧啶二聚化将用于 指出基地机动和定向的要求 DNA高反应性 动力学和产物分析将 确定螺旋和发夹中的反应效率 含有错配或未配对核苷酸的构象。 同时进行的化学和酶研究将产生一个 解释文化的传统和必要背景 光化学结果 1)高锰酸钾对DNA的选择性氧化 将指示胸腺嘧啶碱基的一般可及性 和2）S-1核酸酶催化的链断裂将 证明糖磷酸盐的相关可及性 骨干

An accurate description of NA secondary structure must now include many conformations beyond those represented by a random coil or Watson-Crick double helix. Structural variants such as cruciform, hairpin, and hinged DNA along with the more transiently formed bulged or slipped sequences are often cited as the possible origin of mutational hotspots. Such aberrant conformations may adversely affect both the fidelity of DNA repair and the rate of nucleotide modification. This study has been designed to examine the molecular basis of this latter process by systematically evaluating the effect of duplex structure on the reactivity of DNA in a well defined model system. Photochemical modification of synthetic oligonucleotides serves as the primary method of derivatization and specifically, pyrimidine dimerization will be used to indicate the requirements of base mobility and orientation for DNA hyperreactivity. Kinetic and product analysis will determine the reaction efficiencies in helical and hairpin conformations containing mispaired or unpaired nucleotides. Concurrent chemical and enzymatic studies will generate a traditional and necessary context for interpreting the photochemical results. 1) Selective oxidation of DNA by KMnO4 will indicate the general accessibility of the thymine bases and 2) strand scission catalyzed by S-1 nuclease will demonstrate the related accessibilty of the sugar phosphate backbone.