Hong Haizheng, Wang Yinsheng
Department of Chemistry and Environmental Toxicology Graduate Program, University of California, Riverside, California 92521-0403, USA.
J Am Chem Soc. 2005 Oct 12;127(40):13969-77. doi: 10.1021/ja0531677.
Here, we showed that Pyrex-filtered UV light irradiation of d((Br)CA) gave rise to three types of intrastrand cross-link products, that is, d(C[5-N6]A), d(C[5-2]A), and d(C[5-8]A), where the C5 carbon atom of cytosine is covalently bonded to the N6 nitrogen atom, C2, and C8 carbon atoms of adenine, respectively. Furthermore, we demonstrated by LC-MS/MS that the UV irradiation of a 5-bromocytosine-containing duplex oligodeoxynucleotide (ODN) led to the formation of five cross-link products, that is, C[5-N6]A, C[5-2]A, C[5-8]A, A[2-5]C, and A[8-5]C, under both aerobic and anaerobic conditions. LC-MS/MS quantification results showed that the yields for the formation of these cross-link products are different. The presence of molecular oxygen reduces the yields for the formation of all cross-link products except A[2-5]C. To our knowledge, this is the first report about the formation of intrastrand cross-link products between cytosine and adenine in duplex DNA. The chemistry discovered here may facilitate the future preparations of oxidative cross-link lesion-bearing substrates for biochemical and biophysical studies.
在此，我们表明，对d((Br)CA)进行派热克斯玻璃滤光的紫外线照射会产生三种类型的链内交联产物，即d(C[5-N6]A)、d(C[5-2]A)和d(C[5-8]A)，其中胞嘧啶的C5碳原子分别与腺嘌呤的N6氮原子、C2和C8碳原子共价结合。此外，我们通过液相色谱-串联质谱法（LC-MS/MS）证明，对含5-溴胞嘧啶的双链寡脱氧核苷酸（ODN）进行紫外线照射，在有氧和无氧条件下均会导致形成五种交联产物，即C[5-N6]A、C[5-2]A、C[5-8]A、A[2-5]C和A[8-5]C。LC-MS/MS定量结果表明，这些交联产物的形成产率不同。分子氧的存在会降低除A[2-5]C之外的所有交联产物的形成产率。据我们所知，这是关于双链DNA中胞嘧啶和腺嘌呤之间链内交联产物形成的首次报道。此处发现的化学过程可能有助于未来制备用于生化和生物物理研究的带有氧化交联损伤的底物。
