Poletayev A I, Avdonina T A, Kisselev L L
Nucleic Acids Res. 1974 Feb;1(2):267-78. doi: 10.1093/nar/1.2.267.
Alterations in CD spectra are found in G-containing oligoribonucleotides after modification with kethoxal (beta-ethoxy--alpha-ketobutyraldehyde). Stacking interactions in kethoxalated oligomers are followed by temperature dependence of their CD amplitudes. It is shown that for oligomers with nucleosides in anti-conformation adduct formation destroys the stacking interaction with 3'-neighbour but not with a 5'-neighbour. For nucleosides in non-standard conformation (i.e. syn-conformation of guanine in GpGpCp) the physical alteractions may be seen in those cases, when the substituting group affects the initial conformation or the interplane base contacts via, for instance, blocking NH(2)-group of guanine in GpUp. The results demonstrated that even a single monomer modification in a polymer chain could not be considered as a local event having no influence on the three-dimensional structure. The degree of conformational disorders depends both on the conformation of single nucleotides in the stack and on the nature of the nearest neighbours of the modified base.
在用乙二醛（β-乙氧基-α-酮丁醛）修饰后，含鸟嘌呤的寡核糖核苷酸的圆二色光谱（CD光谱）发生了变化。乙二醛化寡聚物中的堆积相互作用随其CD振幅的温度依赖性而变化。结果表明，对于具有反式构象核苷的寡聚物，加合物的形成破坏了与3'-邻位的堆积相互作用，但不破坏与5'-邻位的堆积相互作用。对于处于非标准构象（即GpGpCp中鸟嘌呤的顺式构象）的核苷，在某些情况下，当取代基团通过例如阻断GpUp中鸟嘌呤的NH₂基团来影响初始构象或平面间碱基接触时，可能会观察到物理相互作用。结果表明，即使聚合物链中的单个单体修饰也不能被视为对三维结构没有影响的局部事件。构象紊乱的程度既取决于堆积中单个核苷酸的构象，也取决于修饰碱基最近邻的性质。
