Seela Frank, Jiang Dawei, Xu Kuiying
Laboratory of Bioorganic Chemistry and Chemical Biology, Center for Nanotechnology, Heisenbergstrasse 11, 48149 Münster, Germany.
Org Biomol Chem. 2009 Sep 7;7(17):3463-73. doi: 10.1039/b908017a. Epub 2009 Jul 6.
Oligodeoxyribonucleotides containing 8-aza-2-deoxyguanosine 9 were synthesized and a new phosphoramidite 11, showing a high coupling yield in solid-phase synthesis, was prepared. Nucleoside 9 was found to be a perfect shape mimic of dG; it forms a strong base pair with dC and shows an excellent mismatch discrimination. Nucleoside 9 appears strongly fluorescent as the anion, and thus, it has unique reporter group properties as a replacement for dG. The pKa-value of 9 (8.4) is lower than that of dG (9.3) and increases from the single-stranded DNA (8.8) to duplex DNA (9.1). The fluorescence of the nucleoside 9 anion is decreased in ss-oligonucleotides and further reduced in duplex DNA. When mismatches of 9 are formed with the four DNA canonical bases, the fluorescence of mismatches is significantly higher than that of the perfectly paired duplex. The fluorescence of the nucleoside 9 anion correlates with the base pair stability.
合成了含有8-氮杂-2'-脱氧鸟苷9的寡脱氧核糖核苷酸，并制备了一种在固相合成中显示出高偶联产率的新型亚磷酰胺11。发现核苷9是dG的完美形状模拟物；它与dC形成强碱基对，并表现出出色的错配识别能力。核苷9作为阴离子时发出强烈荧光，因此，作为dG的替代物，它具有独特的报告基团性质。9的pKa值（8.4）低于dG的pKa值（9.3），并且从单链DNA（8.8）到双链DNA（9.1）会增加。核苷9阴离子的荧光在单链寡核苷酸中降低，在双链DNA中进一步降低。当9与四种DNA标准碱基形成错配时，错配的荧光明显高于完美配对双链体的荧光。核苷9阴离子的荧光与碱基对稳定性相关。
