Chemical and biochemical properties of C8-Aryl-Purine DNA adducts

外源物质（异生物质）与DNA结合形成共价DNA加合物（加成产物）可能会诱导突变，导致癌症形成，或促进细胞死亡，阻断或逆转致癌过程。 已知许多天然产物和化学致癌物经历代谢以形成反应性自由基物质，其共价连接到嘌呤（脱氧鸟苷（dG）和脱氧腺苷（dA））碱基的C8-位点以形成C8-芳基（Ar）-嘌呤加合物。 虽然C8-Ar-嘌呤加合物预计会引发突变，癌症形成和细胞死亡，但对其化学和生物化学性质知之甚少。 这种知识的缺乏限制了我们预测这些加合物如何导致人类疾病的能力。 因此，这个NSERC资助的项目的目标是填补我们对C8-Ar-嘌呤加合物形成后果的理解中的这一空白。 在我们的研究计划的这一阶段，我们表征了它们对双链体DNA结构、DNA复制的影响，并开始评估它们的化学反应性。我们已经建立了C8-Ar-嘌呤加合物定点掺入DNA的合成策略。 利用光学光谱来确定它们对双链体DNA稳定性和结构的影响。 包括在这个方面的项目是使用C8-Ar-嘌呤加合物作为分子传感器和作为氧化还原活性的核碱基，作为优先目标的进一步氧化双链体DNA。 引物延伸研究，利用聚丙烯酰胺凝胶电泳（PAGE）与DNA聚合酶，以测量插入的核苷酸相对的C8-Ar-嘌呤加合物和链延伸的3 '-末端也提出了。 由于加合物修饰的DNA的复制涉及DNA聚合酶，这些研究将开始评估C8-Ar-嘌呤加合物的生物学影响，这将对化学，生物学和医学研究人员具有广泛的科学价值。

Attachment of a foreign substance (xenobiotic) to DNA to form a covalent DNA adduct (addition product) may induce mutations causing cancer formation, or facilitate cell death and block or reverse the carcinogenic process. A number of natural products and chemical carcinogens are known to undergo metabolism to form reactive radical species that attach covalently to the C8-site of purine (deoxyguanosine (dG) and deoxyadenosine (dA)) bases to form C8-aryl(Ar)-purine adducts. While C8-Ar-purine adducts are expected to initiate mutations, cancer formation and cell death, very little is known about their chemical and biochemical properties. This lack of knowledge limits our ability to predict how these adducts will contribute to human disease. Thus, the goal of this NSERC-funded project is to fill this gap in our understanding of the consequences of C8-Ar-purine adduct formation. In this phase of our research program we characterize their impact on duplex DNA structure, DNA replication and begin to assess their chemical reactivity. We have established synthetic strategies for the site-specific incorporation of C8-Ar-purine adducts into DNA. Optical spectroscopies are utilized to determine their impact on duplex DNA stability and structure. Included in this aspect of the project is the use of C8-Ar-purine adducts as molecular sensors and as redox-active nucleobases that act as preferential targets of further oxidation within duplex DNA. Primer extension studies utilizing polyacrylamide gel electrophoresis (PAGE) with DNA polymerases to measure insertion of nucleotides opposite a C8-Ar-purine adduct and chain extension from the 3'-terminus are also proposed. As the replication of adduct-modified DNA involves DNA polymerases, these studies will begin to assess the biological impact of C8-Ar-purine adducts, which will be of broad scientific value to researchers in chemistry, biology and medicine.