PHOTOCHEMISTRY OF DNA NUCLEOBASES

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 紫外线被活细胞吸收后会引起一系列效应，如遗传突变、细胞死亡和细胞转化。这些后一种类型的损伤至少部分是由细胞基因组DNA中形成的光产物介导的。我们工作的一个主要重点是次要碱基5-甲基胞嘧啶(M5C)在介导光吸收引起的损伤中的作用，尽管胸腺嘧啶(THY)和胞嘧啶(Cyt)的反应性也在进行中。我们的主要目标是分离和鉴定一些我们认为可能与实现对紫外线诱导的DNA损伤的化学理解相关的光产物。目前感兴趣的化合物是M5C与Cyt和Ty的(6-4)加合物和杜瓦加合物，既有碱基形式，也有核苷形式，以及与细胞内DNA环境中的分子(如水、蛋白质中的氨基酸)形成的加合物。这些化合物的制备过程避免了这些化合物不稳定的条件。高效液相色谱(HPLC)被用来分离各种纯状态的化合物。使用质子和碳-13核磁共振光谱、紫外光谱、电喷雾电离和MALDI质谱学以及适当的圆二色谱对它们进行了结构表征。它们在DNA消化条件下的化学稳定性也在测定中。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. 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) and cytosine (Cyt) 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. 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.