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

外来物质（异种生物）附着在DNA上，形成共价DNA加合物（加成产物），可诱导导致癌症形成的突变，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过代谢形成活性自由基，共价附着在嘌呤的c8位点（脱氧鸟苷（dG）和脱氧腺苷（dA））碱基上，形成c8 -芳基(Ar)-嘌呤加合物。虽然c8 - ar -嘌呤加合物有望引发突变、癌症形成和细胞死亡，但人们对它们的化学和生化特性知之甚少。这种知识的缺乏限制了我们预测这些加合物将如何导致人类疾病的能力。因此，这个nserc资助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空白。在我们研究计划的这个阶段，我们描述了它们对双链DNA结构、DNA复制的影响，并开始评估它们的化学反应性。我们已经建立了将c8 - ar -嘌呤加合物结合到DNA中的合成策略。利用光谱学来确定它们对双链DNA稳定性和结构的影响。该项目的这一方面包括使用c8 - ar -嘌呤加合物作为分子传感器和氧化还原活性核碱基，作为双工DNA进一步氧化的优先目标。引物延伸研究也提出了利用DNA聚合酶的聚丙烯酰胺凝胶电泳（PAGE）来测量c8 - ar -嘌呤加合物对面核苷酸的插入和从3'端延伸的链。由于加合物修饰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.