PHOTOCHEMICAL STUDIES OF HALOGENATED PYRIMIDINES IN DNA

DNA 中卤代嘧啶的光化学研究

• 批准号: 3186241
• 负责人: RONALD O RAHN
• 金额: $ 9.81万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 1986
• 资助国家: 美国
• 起止时间: 1986-12-01 至 1989-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3186241
• 关键词: biological models; bromodeoxyuridine; free radicals; gel electrophoresis; haloaminoacid; halogenation; idoxuridine; ionizing radiation; nonvisual photosensitivity; nucleic acid sequence; oligonucleotides; photochemistry; pyrimidine nucleotides; radiation genetics; radiation sensitivity; radiosensitizer

The purpose of the proposed research is to arrive at a better understanding of how halogenated pyrimidines can be used as radiosensitizers in radiobiology and cancer therapy. Comparisons will be made between iododeoxyuridine (IdUrd) and bromodeoxyuridine (BrdUrd) as radiation sensitive thymidine analogs. Attempts will be made to correlate similarities and differences in behavior at the macroscopic level with the photochemical properties of the individual deoxynucleosides, particularly as to how these properties are modified upon incorporation into an ordered polymer. Various methods will be examined for measuring the release of the halogen atom into the solvent following radiation. The methodology developed will be used to monitor radiation induced changes as a function of a variety of experimental parameters. A sensitive method for measuring low levels of either I- or Br- will be used to monitor the uptake of halogenated base analogs into the DNA of exposed cells. This method will also be used to investigate the mechanism by which 33258 Hoechst plus 365 nm irradiation induces dehalogenation in substituted DNA. The chemical reactivity of the uracil-5-yl radical or the secondary racials induced by it will be studied in order to better understand the mechanisms of formation of chain breaks, alkali-labile bonds, protein DNA cross links, and the 5,5' -diuracilyl coupled product. Previous studies on the extent of energy transfer in IdUrd-DNA will be extended to BrdUrd-DNA and will involve excitation spectral analysis as a function of the state of the DNA. The sequence dependence of the photolysis in defined oligonucleotides or polynucleotides will be examined by means of polyacrylamide gel electrophoresis and high resolution proton magnetic resonance spectroscopy. Oligonucleotides will be prepared containing BrdUrd or IdUrd in fixed positions relative to variable neighboring sequences. The influence of neighboring bases on the rate of photolysis and the nature of the sugar damage will be reflected in the location and intensity of the bands on the gels and in the modification of the PMR for those sugar protons directly effected by hydrogen abstraction.

拟议研究的目的是为了更好地理解 卤代嘧啶如何用作放射增敏剂 放射生物学和癌症治疗。 之间将进行比较 碘脱氧尿苷 (IdUrd) 和溴脱氧尿苷 (BrdUrd) 作为辐射 敏感的胸苷类似物。 将尝试关联 宏观层面行为的异同 各个脱氧核苷的光化学性质，特别是 至于如何在合并到有序中时修改这些属性 聚合物。 将检查各种方法来测量释放 卤素原子在辐射后进入溶剂。 方法论 开发的将用于监测辐射引起的变化作为函数 各种实验参数。 灵敏的测量方法 低水平的 I- 或 Br- 将用于监测 卤化碱基类似物进入暴露细胞的 DNA 中。 这个方法将 也可用于研究 33258 Hoechst plus 365 的作用机制 nm 辐射诱导取代 DNA 脱卤。 化学品 尿嘧啶-5-基自由基或由以下因素引起的次级种族的反应性 将对其进行研究，以便更好地了解其机制 链断裂、碱不稳定键、蛋白质 DNA 交联的形成， 和5,5'-二尿嘧啶偶联产物。 先前的研究范围 IdUrd-DNA 中的能量转移将扩展到 BrdUrd-DNA 并将 涉及激发光谱分析作为状态的函数 脱氧核糖核酸。 特定寡核苷酸中光解作用的序列依赖性 或多核苷酸将通过聚丙烯酰胺凝胶进行检查 电泳和高分辨率质子磁共振 光谱学。 将制备含有 BrdUrd 或 IdUrd 的寡核苷酸 相对于可变的相邻序列处于固定位置。 这 邻近碱基对光解速率和性质的影响 糖损伤将反映在糖损伤的位置和强度上 凝胶上的条带以及这些糖的 PMR 修饰 质子直接受氢夺取影响。