STRUCTURAL IDENTIFICATION AND CHARACTERIZATION OF A NEW DNA PHOTOPRODUCT

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。 DNA合成超过胞嘧啶和含5-甲基胞嘧啶的顺式嘧啶二聚体的脱氨基产物可能是阳光诱导与皮肤癌相关的C-T转换突变的主要机制之一。为了更好地了解控制光产物脱氨反应的构效关系，我们设计了含有唯一TC位点的ODN序列d(GTATCATGAGGTGC)，使其能够在紫外光照射下制备DT[c，S]C二聚体，以测量胞嘧啶光产物的脱氨动力学。在d(GTATCATGAGGTGC)的UVB(312 Nm)照射过程中，除了预期的T[c，S]C光产物外，一个具有异常短的保留时间的丰富的未知物质引起了我们的注意。该产品仅在低pH值(6以下)下出现。我们的目标是通过结合各种技术，如高效液相色谱、质谱学、核磁共振和X射线结晶学来阐明这一未知的主要光产物的结构。

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. DNA synthesis past deamination products of cytosine and 5-methylcytosine-containing cis-syn pyrimidine dimer photoproducts may be one of the principal mechanisms by which sunlight induces C-to-T transition mutations linked to skin cancer. To understand better the structure-activity relationships governing photoproduct deamination, we designed the ODN sequence d(GTATCATGAGGTGC) containing a unique TC site to enable preparation of a dT[c,s]C dimer by UV irradiation to measure the kinetics of deamination of cytosine photoproducts. Instead of the expected T[c,s]C photoproduct, an abundant unknown with an unusually short HPLC retention time attracted our attention during the course of UVB irradiation (312 nm) of d(GTATCATGAGGTGC). This product only appeared at low pH (below 6). Our goal is to elucidate the structure of this unknown major photoproduct by combining various techniques such as HPLC, mass spectrometry, NMR, and X-Ray crystallography.