Nitrosamine Chemistry and Biochemistry

描述(申请人提供)：这项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，人类通过内源形成和环境来源接触到亚硝胺。大多数被研究的亚硝胺在Ames试验中被肝微粒体激活时是致癌或致突变的。亚硝胺存在于地下水、食品、个人护理产品和烟草产品中，在许多工业环境中都会遇到亚硝胺，特别是在橡胶制造和硫化设施、金属和皮革加工企业。最简单的亚硝胺表现其有害行为的机制是相当清楚的。它们往往以DNA的氧原子为目标。通过它们形成的加合物，它们导致复制聚合酶在这些损伤相反的位置错误插入，导致突变。一些基本方面还不清楚--例如，为什么亚硝胺形成的重氮离子倾向于以氧原子为目标，为什么会有突变/加合物沉积热点。这项提案包含了最终可以解决这些问题的试验性方法。该提案还试图了解一种“非简单的”亚硝胺--N-亚硝基吗啉(NMOR)--的更复杂的化学成分--人类接触到这种物质。该实验室最近的工作表明，NMOR的代谢物分解生成新结构的核苷加合物，这些加合物含有侧链醛。这些物质慢慢分解成羟乙基病变。这种侧醛加合物很可能来自其他来源，如其他亚硝胺、DNA氧化和脂质过氧化的产物以及其他环境毒物。目的是了解代谢物的损伤光谱，了解它是如何随时间演变的，以及在寡核苷酸中构建新的加合物，并通过核磁共振和捕集研究它们的结构和交联活性。新的技术和合成方法的结合被整合在一起，以全面和详细地了解DNA损伤的基本方面和具有广泛应用的结构。

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.