Laboratory of Bioorganic Chemistry and Chemical Biology, Center for Nanotechnology , Heisenbergstraße 11, 48149 Münster, Germany.
J Org Chem. 2012 Jan 6;77(1):188-99. doi: 10.1021/jo202103q. Epub 2011 Dec 14.
7-Deazapurine and 8-aza-7-deazapurine nucleosides related to dA and dG bearing 7-octadiynyl or 7-tripropargylamine side chains as well as corresponding oligonucleotides were synthesized. "Click" conjugation with 1-azidomethyl pyrene (10) resulted in fluorescent derivatives. Octadiynyl conjugates show only monomer fluorescence, while the proximal alignment of pyrene residues in the tripropargylamine derivatives causes excimer emission. 8-Aza-7-deazapurine pyrene "click" conjugates exhibit fluorescence emission much higher than that of 7-deazapurine derivatives. They are quenched by intramolecular charge transfer between the nucleobase and the dye. Oligonucleotide single strands decorated with two "double clicked" pyrenes show weak or no excimer fluorescence. However, when duplexes carry proximal pyrenes in complementary strands, strong excimer fluorescence is observed. A single replacement of a canonical nucleoside by a pyrene conjugate stabilizes the duplex substantially, most likely by stacking interactions: 6-12 °C for duplexes with a modified "adenine" base and 2-6 °C for a modified "guanine" base. The favorable photophysical properties of 8-aza-7-deazapurine pyrene conjugates improve the utility of pyrene fluorescence reporters in oligonucleotide sensing as these nucleoside conjugates are not affected by nucleobase induced quenching.
7-脱氮嘌呤和 8-氮杂-7-脱氮嘌呤核苷类似物与 dA 和 dG 结合，具有 7-辛二炔基或 7-三丙炔胺侧链以及相应的寡核苷酸被合成。用 1-叠氮甲基芘（10）进行“点击”共轭得到荧光衍生物。辛二炔基共轭物仅显示单体荧光，而三丙炔胺衍生物中芘残基的近端排列导致激基发射。8-氮杂-7-脱氮嘌呤芘“点击”共轭物表现出比 7-脱氮嘌呤衍生物更高的荧光发射。它们被碱基和染料之间的分子内电荷转移猝灭。用两个“双点击”芘修饰的单链寡核苷酸显示出弱或无激基荧光。然而，当双链在互补链中带有近端芘时，会观察到强激基荧光。单个嘧啶共轭物取代规范核苷会显著稳定双链，很可能是通过堆积相互作用：带有修饰的“腺嘌呤”碱基的双链稳定 6-12°C，带有修饰的“鸟嘌呤”碱基的双链稳定 2-6°C。8-氮杂-7-脱氮嘌呤芘共轭物的有利光物理性质提高了芘荧光报告物在寡核苷酸传感中的应用，因为这些核苷类似物不受碱基诱导猝灭的影响。
