PHOTOCHEMISTRY OF DNA NUCLEOBASES AND RELATED COMPOUNDS

这个子项目是许多利用资源的研究子项目之一 由NIH/NCRR资助的中心拨款提供。子项目的主要支持 而子项目的主要调查员可能是由其他来源提供的， 包括其它NIH来源。 列出的子项目总成本可能 代表子项目使用的中心基础设施的估计数量， 而不是由NCRR赠款提供给子项目或子项目工作人员的直接资金。 已知紫外线（UV）光在被活细胞吸收后引起许多效应，例如基因突变、细胞死亡和细胞转化。 这些后一种类型的损伤至少部分地由细胞基因组DNA中形成的光产物介导。我们工作的一个主要重点是次要碱基5-甲基胞嘧啶（m5 C）在介导光吸收引起的损伤中的作用，尽管胸腺嘧啶（Thy），胞嘧啶（Cyt）和卤代尿嘧啶（例如5-溴尿嘧啶）的反应性的调查也正在进行中。 我们的主要目的是针对隔离和表征的一些光产物，我们认为可能是相关的实现化学的理解紫外线诱导的DNA损伤。 目前感兴趣的化合物是m5 C与Cyt和Thy的（6-4）加合物和杜瓦加合物，两者都是核碱基和核苷形式，以及在细胞中DNA环境中与分子（例如水、蛋白质中的氨基酸）形成的加合物上。 这些化合物是利用避免这些化合物不稳定的条件的方法制备的。 高效液相色谱法（HPLC）用于分离纯态的各种化合物。 使用质子和碳-13 NMR光谱、UV光谱、电喷雾电离和MALDI质谱以及适当的圆二色性光谱对它们进行结构表征。它们在DNA消化条件下的化学稳定性也正在测定中。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Ultraviolet (UV) light is known to cause a number of effects after absorption by living cells, such as genetic mutation, cell death and cellular transformation. These latter types of damage are mediated, at least in part, by photoproducts formed in the genomic DNA of the cell. One main focus of our work is on the role of the minor base 5-methylcytosine (m5C) in mediating damage induced by absorption of light, although investigations of the reactivity of thymine (Thy), cytosine (Cyt) and halogenated uracils (e.g. 5-bromouracil) are also being carried out. Our primary aim is directed towards isolating and characterizing a number of photoproducts that we believe could be relevant to achieving a chemical understanding of UV-induced DNA damage. Among the compounds of current interest are the (6-4) adducts and Dewar adducts of m5C with Cyt and Thy, both in nucleobase and nucleoside form and on adducts formed with molecules in the environment of DNA in the cell (e.g. water, amino acids in proteins). These compounds are being prepared utilizing procedures that avoid conditions under which these compounds are unstable. High performance liquid chromatography (HPLC) is being used to isolate the various compounds in a pure state. They are being structurally characterized using proton and carbon-13 NMR spectroscopy, UV spectroscopy, electrospray ionization and MALDI mass spectrometry and, where appropriate, circular dichroic spectroscopy. Their chemical stability under conditions of DNA digestion is also being determined.