Lankhorst P P, van der Marel G A, Wille G, van Boom J H, Altona C
Nucleic Acids Res. 1985 May 10;13(9):3317-33. doi: 10.1093/nar/13.9.3317.
All 36 ribose proton resonances and most of the base proton resonances of the hexanucleoside pentaphosphate AUAUAU have been assigned unequivocally using 2D J-resolved spectroscopy, spin echo correlated spectroscopy (SECSY) and 2D NOE spectroscopy (NOESY). The NMR parameters of AUAUAU are compared with those of smaller fragments that contain methylated adenine bases: m62AU, m62AUm62A, m62AUm62AU and m62AUm62AUm62A. Previous studies on this series of compounds have shown that in all these cases purine-pyrimidine-purine sequences prefer to adopt a mixture of states which have as common feature that the interior pyrimidine residues are bulged out, whereas the purine residues stack upon each other. Chemical shift data, proton-proton coupling constants, as well as the observation of imino-proton resonances for AUAUAU show unambiguously that upon lowering the temperature the high-temperature "bulged out" situation reverts to a normal A-RNA-like double helix.
利用二维J分辨光谱、自旋回波相关光谱(SECSY)和二维核Overhauser效应光谱(NOESY),已明确归属了六磷酸五核苷AUAUAU的所有36个核糖质子共振峰以及大部分碱基质子共振峰。将AUAUAU的核磁共振参数与含有甲基化腺嘌呤碱基的较小片段:m62AU、m62AUm62A、m62AUm62AU和m62AUm62AUm62A的参数进行了比较。此前对该系列化合物的研究表明,在所有这些情况下,嘌呤-嘧啶-嘌呤序列倾向于采取多种状态的混合,其共同特征是内部嘧啶残基向外凸出,而嘌呤残基相互堆叠。AUAUAU的化学位移数据、质子-质子耦合常数以及亚氨基质子共振的观测结果明确表明,随着温度降低,高温下“向外凸出”的状态会转变为类似正常A-RNA的双螺旋结构。