STRUCTURAL IDENTIFICATION AND CHARACTERIZATION OF A NEW DNA PHOTOPRODUCT

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。 DNA合成过去的脱氨基产物的胞嘧啶和5-甲基胞嘧啶的顺式-syn嘧啶二聚体的光产物可能是其中一个主要的机制，阳光诱导的C到T的转换突变与皮肤癌。 为了更好地理解光产物脱氨基的结构-活性关系，我们设计了含有独特TC位点的ODN序列d（GTATCATGAGGTGC），以使得能够通过UV照射制备dT[c，s]C二聚体来测量胞嘧啶光产物脱氨基的动力学。 而不是预期的T[c，s]C的光产物，一个丰富的未知的异常短的HPLC保留时间吸引了我们的注意力在UVB照射（312 nm）的过程中的d（GTATCATGAGGTGC）。该产物仅在低pH（低于6）下出现。我们的目标是通过结合各种技术，如HPLC，质谱，NMR和X射线晶体学来阐明这种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. 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. 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.