Tsunoda Hirosuke, Kudo Tomomi, Ohkubo Akihiro, Seio Kohji, Sekine Mitsuo
Department of Life Science, Tokyo Institute of Technology, 4259 Nagatsuta, Midoriku, Yokohama, 226-8501, Japan.
Nucleic Acids Symp Ser (Oxf). 2008(52):445-6. doi: 10.1093/nass/nrn226.
The main products obtained by oxidation of cytosine and adenine bases with hydrogen peroxide are cytosine and adenine N-oxide derivatives. There is a possibility that these N-oxide derivatives are mutagenic in genomic DNA, such as 8-oxoguanine or thymine glycol. Although the chemical synthesis and properties of 2'-deoxynucleoside N-oxide derivatives have been well established, little has been reported about the chemical and biochemical behavior of DNA oligomers containing these modified 2'-deoxynucleoside. In this study, we examined their base recognition ability by T(m) experiments and computer modeling, and their substrate specificity in enzyme reaction. It was found that the T(m) values of in DNA-DNA, DNA-RNA duplexes incorporating 2'-deoxynucleoside N-oxide derivatives were significant low, while the one-point incorporation of these modified derivatives into the 3'-terminal site of a DNA oligomer by DNA polymerase occurred accurately selecting the complementary G or T base on a template DNA oligomer.
用过氧化氢氧化胞嘧啶和腺嘌呤碱基得到的主要产物是胞嘧啶和腺嘌呤的N-氧化物衍生物。这些N-氧化物衍生物有可能在基因组DNA中具有致突变性，例如8-氧代鸟嘌呤或胸腺嘧啶二醇。尽管2'-脱氧核苷N-氧化物衍生物的化学合成和性质已得到充分确立，但关于含有这些修饰的2'-脱氧核苷的DNA寡聚物的化学和生化行为的报道却很少。在本研究中，我们通过T(m)实验和计算机建模研究了它们的碱基识别能力，以及它们在酶反应中的底物特异性。结果发现，掺入2'-脱氧核苷N-氧化物衍生物的DNA-DNA、DNA-RNA双链体的T(m)值显著降低，而DNA聚合酶将这些修饰的衍生物单点掺入DNA寡聚物的3'-末端位点时，能够准确地选择模板DNA寡聚物上互补的G或T碱基。
