Nitrosamine Chemistry and Biochemistry

描述（由申请人提供）：本研究的长期目标是了解致癌亚硝胺化学的基本和应用方面。亚硝胺是一大类结构各异的化合物，人类通过内源性形成和环境来源接触到亚硝胺。在艾姆斯试验中，大多数研究的亚硝胺被肝微粒体激活时具有致癌性或致突变性。亚硝胺存在于地下水、食品、个人护理产品和烟草产品中，并在许多工业环境中遇到，特别是在橡胶制造和硫化设施、金属和皮革加工企业中。最简单的亚硝胺表现其有害作用的机理是相当好理解的。它们往往以DNA的氧原子为目标。通过它们形成的加合物，它们引起复制性聚合酶错误插入这些损伤的对面，导致突变。一些基本方面还没有很好地理解-例如，为什么从亚硝胺形成的重氮离子倾向于靶向氧原子，为什么有突变/加合物沉积热点。该提案载有最终解决这些问题的实验性办法。该提案还试图了解人类接触的“非简单”亚硝胺- N-亚硝基吗啉（NMOR）的更复杂的化学性质。该实验室最近的工作表明，NMOR的代谢产物分解产生新结构的核苷加合物，这些加合物含有侧基醛。这些慢慢分解为羟乙基损伤。这种侧链醛加合物可能广泛存在于其他亚硝胺、DNA氧化和脂质过氧化产物以及其他环境毒物中。其目的是了解来自代谢产物的损伤谱，它如何随时间演变，并构建寡核苷酸中的新型加合物，并通过NMR和捕获研究来研究其结构和交联活性。新的技术和合成方法的组合被整合到一个完整的和详细的理解的基本方面的DNA损伤和结构，具有广泛的应用。

DESCRIPTION (provided by applicant): The long term goal of this research is to understand fundamental and applied aspects of the chemistry of carcinogenic nitrosamines. Nitrosamines are a large class of compounds of varied structure to which there is human exposure through endogenous formation and environmental sources. Most of the nitrosamines investigated are carcinogenic or mutagenic in the Ames test when activated by liver microsomes. Nitrosamines are found in groundwater, foods, personal care products, and tobacco products and are encountered in a number of industrial environs, in particular in rubber manufacturing and curing facilities, metal and leather working concerns. The mechanism by which the simplest nitrosamines manifest their deleterious actions is reasonably well understood. They tend to target the oxygen atoms of DNA. By means of the adducts they form they cause replicative polymerases to mis-insert opposite these lesions leading to mutation. Some fundamental aspects are not well understood - for example why the diazonium ions formed from nitrosamines tend to target the oxygen atoms and why there are mutation/adduct deposition hotspots. This proposal contains experimental approaches by which these issues can finally be resolved. The proposal also seeks to understand the more complex chemistry of a "non-simple" nitrosamine - N- Nitrosomorpholine (NMOR) - to which there is human exposure. Recent work from this laboratory has demonstrated that a metabolite of NMOR decomposes to give nucleoside adducts of novel structure, ones that contain a pendant aldehyde. These slowly decompose to hydroxyethyl lesions. Such pendant aldehyde adducts are likely widely encountered from sources such as other nitrosamines and the products of DNA oxidation and lipid peroxidation as well as other environmental toxicants. It is intended to understand the damage spectrum derived from the metabolite, how it evolves with time and also to construct the novel adducts in oligonucleotides and to study their structure and cross-linking activities by NMR and trapping studies. The combination of novel technical and synthetic approaches are integrated toward a complete and detailed understanding of fundamental aspects of DNA damage and structures that have broad application.