Development of Novel Spin-labeled Nucleosides which detect base-pairing

我们设计了一种新型的自旋标记核苷，其中一个自旋源N-叔丁基氨氧基直接连接到碱基上。合成了2-N-叔丁基氨氧基腺苷、2-N-叔丁基氨氧基肌苷、8-N-叔丁基氨氧基肌苷和5-N-叔丁基氨氧基胞苷，并用电子顺磁共振(EPR)研究了它们的稳定性和性质。研究N-叔丁氨基氧基核苷的EPR谱是否会随着与互补碱氢键的形成而发生变化。O-硅化-5-N-叔丁基氨基氧基胞苷在CH_2Cl2中的EPR谱随O-硅化鸟苷的加入而发生变化，可能与氨氧基胞苷形成氢键。将2-N-叔丁基氨基氧基腺苷引入到寡核苷酸中，测定了其EPR谱。所得寡核苷酸的EPR谱在磷酸盐缓冲液中有三条谱线。当与互补链形成双链时，高线消失，表明EPR谱可能提供有关寡核苷酸结构的有用信息。2-N-叔丁基氨氧基肌苷的EPR谱表明，由于嘌呤部分的结构变化，其具有pH依赖性

We designed novel spin-labeled nucleosides, in which a spin source, an N-tert-butylaminoxyl radical, was directly attached to nucleobase. 2-N-tert-Butylaminoxyladenosine, 2-N-tert-butylaminoxylinosine, and 8-N-tert-butylaminoxylinosine, and 5-N-tert-butylaminoxylcytidine derivative were synthesized and thier stabilities and properties were studied by using electron peramagnetic resonance(EPR). It was of interest to investigate if EPR spectra of N-tert-butylaminoxylnucleosides changed upon formation of hydrogen bonding with complementary base. EPR spectra of O-silylated-5-N-tert-butylaminoxylcytidine in CH_2Cl_2 changed upon addition of O-silylated guanosine, which might form hydrogen bonds with the aminoxyl cytidine. 2-N-tert-Butylaminoxyladenosine was introduced into oligoncleotide and its EPR spectra were measured. The EPR spectrum of the obtained oligonucleotide showed three lines in phosphate buffer. The high line disappeared upon duplex formation with the complementary strand to show that the EPR spectra might give useful information on the structure of oligonucleotide. EPR spectra of 2-N-tert-butylaminoxylinosine showed pH dependency due to structural change of purine moiety