OXIDATIVE DNA DAMAGE AND EXOCYCLIC DNA ADDUCTS

这个应用程序的重点是在DNA双链体水平的结构比对 与脱碱基位点、环外加合物、8-氧代嘌呤损伤和 芳族胺加合物在化学和生物化学中起关键作用， 辐射诱发的致癌作用。 这些的解决方案结构 病变将通过核磁共振和分子动力学的组合来定义 在定义的序列上下文中进行细化。 我们的基础知识的新方向 位点研究将集中在含有相对缺失的无碱基位点上 难治性的病变和双链无碱基位点病变 修复. 这些结构研究将扩展到核糖内酯 作为孤立病变和作为双链病变相关的脱碱基位点 新癌抑制素的作用。 环外加合物的研究将是 延伸至乙烯基的乙烯基环外加合物 氯化物与脱氧鸟嘌呤、脱氧腺嘌呤和脱氧胞苷。 我们将 探测环外加合物和环外加合物的顺式排列的一般性， 适应周期外的结构扰动的程度 螺旋内的环。 结构研究将与 选择性识别这些外环的DNA糖基化酶的研究 加合物取决于病变部位对面的碱基。 我们计划 脱氧鸟嘌呤氧化损伤的比较结构研究 和脱氧腺嘌呤在相同的序列背景下， 与8-oxo-相比，8-oxo-Dg的致突变性增强的起源 无致突变性。 还将尝试描述 脱氧嘌呤在DNA寡聚体上的咪唑开环FAPY加合物 水平 我们以前对碱基替换比对的结构研究 在C8-脱氧鸟嘌呤芳族胺加合物位点被扩展到 特定序列背景下的单缺失和双缺失移码 从体外复制研究中建立。 我们的努力将尝试 确定（AAF）Dg和（AF）Dg在移码位点的构象 并确定与单个和 双重缺失 这种比较分析还将扩大到 抗氧化致癌物（ABP）Dg和食物毒素（PhIP）Dg加合物 以评估芳族胺环系统对 病变部位的结构排列。 总体目标是将 我们的核磁共振结构研究与相关的量热测量 在Ken Breslauer教授的实验室里， 在弗朗西斯约翰逊教授的实验室制备的。 这些研究将 提供必要的结构热力学框架， 解释教授实验室中的诱变实验。 亚瑟·格罗曼和约翰·埃西格曼。

This application focuses on structural alignments at the DNA duplex level associated with abasic sites, exocyclic adducts, 8-oxo-purine lesions and aromatic amine adducts which play a critical role in chemical and radiation induced carcinogenesis. The solution structure of these lesions will be defined by a combination of NMR and molecular dynamics refinements in defined sequence contexts. New directions in our abasic site research will focus on abasic sites containing deletions opposite the lesion and bistrand abasic site lesions which are refractory to repair. These structural studies will be extended to ribonolactone abasic sites both as isolated lesions and as bistrand lesions relevant to neocarcinostatin action. The exocyclic adduct research will be extended to etheno exocyclic adducts of the potent carcinogen vinyl chloride with deoxyguanine, deoxyadenine and deoxycytidine. We shall probe the generality of syn alignments at the exocyclic adduct and the extent of structural perturbations necessary to accommodate the exocyclic ring within the helix. The structural research will be correlated with research on DNA glycosylases which selectively recognize these exocyclic adducts depending on the base opposite the lesion site. We plan a comparative structural investigation of oxidative damage at deoxyguanine and deoxyadenine in the same sequence context in an attempt to understand the origin of the enhanced mutagenicity of 8-oxo-Dg in contrast to 8-oxo- Da which is non-mutagenic. An attempt will be also made to characterize imidazole ring-opened FAPY adducts of deoxypurines at the DNA oligomer level. Our previous structural research on base substitution alignments at C8-deoxyguanine aromatic amine adduct sites are being extended to single and double deletion frame-shifts in specific sequence contexts established from in vitro replication studies. Our efforts will attempt to define the conformation of (AAF)Dg and (AF) Dg at the frame-shift site and identify the structural differences associated with a single and double deletions. Such a comparative analysis will also be extended to the anti-oxidant carcinogen (ABP)Dg and the food toxin (PhIP)Dg adducts to evaluate contributions from the aromatic amine ring system to structural alignments at the lesion site. The overall goal is to couple our NMR structural investigations with related calorimetric measurements in Prof. Ken Breslauer's laboratory on these four families of DNA lesions prepared in Prof. Francis Johnson's laboratory. These studies will provide the structural-thermodynamics framework necessary for interpretation of mutagenesis experiments in the laboratories of Profs. Arthur Grollman and John Essigmann.