Department of Chemistry, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
J Am Chem Soc. 2011 Jan 12;133(1):42-50. doi: 10.1021/ja106158b. Epub 2010 Nov 10.
Direct radical addition reactions at the C(8)-site of 2'-deoxyguanosine (dG) can afford C(8)-Ar-dG adducts that are produced by carcinogenic arylhydrazines, polycyclic aromatic hydrocarbons, and certain phenolic toxins. Such modified nucleobases are also highly fluorescent for sensing applications and possess useful electron transfer properties. The site-specific synthesis of oligonucleotides containing the C(8)-Ar-G adduct can be problematic. These lesions are sensitive to acids and oxidants that are commonly used in solid-phase DNA synthesis and are too bulky to be accepted as substrates for enzymatic synthesis by DNA polymerases. Using the Suzuki-Miyaura cross-coupling reaction, we have synthesized a number of C(8)-Ar-G-modified oligonucleotides (dimers, trimers, decamers, and a 15-mer) using a range of arylboronic acids. Good to excellent yields were obtained, and the reaction is insensitive to the nature of the bases flanking the convertible 8-Br-G nucleobase, as both pyrimidines and purines are tolerated. The impact of the C(8)-Ar-G lesion was also characterized by electrospray ionization tandem mass spectrometry, UV melting temperature analysis, circular dichroism, and fluorescence spectroscopy. The C(8)-Ar-G-modified oligonucleotides are expected to be useful substrates for diagnostic applications and understanding the biological impact of the C(8)-Ar-G lesion.
直接在 2'-脱氧鸟苷（dG）的 C(8)-位进行自由基加成反应，可以得到由致癌芳肼、多环芳烃和某些酚类毒素产生的 C(8)-芳基-dG 加合物。这种修饰的碱基在用于传感应用时具有高度的荧光性，并具有有用的电子转移性质。含有 C(8)-芳基-G 加合物的寡核苷酸的定点合成可能会有问题。这些损伤对固相 DNA 合成中常用的酸和氧化剂很敏感，而且体积太大，不能被 DNA 聚合酶作为酶合成的底物接受。我们使用铃木-宫浦交叉偶联反应，使用一系列芳基硼酸合成了许多 C(8)-芳基-G 修饰的寡核苷酸（二聚体、三聚体、十聚体和十五聚体）。得到了良好到优秀的产率，并且该反应对可转换的 8-Br-G 碱基侧翼的碱基的性质不敏感，因为嘧啶和嘌呤都可以被容忍。C(8)-芳基-G 损伤的影响也通过电喷雾电离串联质谱、UV 熔点分析、圆二色性和荧光光谱进行了表征。C(8)-芳基-G 修饰的寡核苷酸有望成为诊断应用和理解 C(8)-芳基-G 损伤的生物学影响的有用底物。
