Lancelot G, Guesnet J L, Roig V, Thuong N T
Centre de Biophysique Moléculaire, CNRS, Orléans, France.
Nucleic Acids Res. 1987 Sep 25;15(18):7531-47. doi: 10.1093/nar/15.18.7531.
The unnatural oligonucleotide alpha-d(TCTAAAC) was synthesized and was found more resistant towards endonucleases than its beta-analog. 2D-NMR experiments allowed the assignment of all non-exchangeable aromatic and sugar protons except for the overlapping 5' -5" resonances, as well as the exchangeable imino protons of the parallel hybrid duplex alpha-d (TCTAAAC)-beta-d(AGATTTG). NMR studies show that the strength of the association between the alpha-strand and the beta parallel strand is equivalent to that between their anti-parallel complementary beta-analogs beta-d(CAAATCT) and beta-d(AGATTTG). NOE data provide evidence that both duplexes form stable right-helical duplexes with an anti-conformation on the glycosyl linkages and a Watson-Crick pairing. NOESY and COSY spectra allowed us to determine that alpha and beta deoxyriboses adopt a 3' -exo conformation.
合成了非天然寡核苷酸α-d(TCTAAAC)，发现它比其β类似物对核酸内切酶更具抗性。二维核磁共振实验确定了除重叠的5'-5''共振外所有不可交换的芳香族和糖质子，以及平行杂交双链体α-d(TCTAAAC)-β-d(AGATTTG)中可交换的亚氨基质子。核磁共振研究表明，α链与β平行链之间的缔合强度与它们的反平行互补β类似物β-d(CAAATCT)和β-d(AGATTTG)之间的缔合强度相当。核Overhauser效应（NOE）数据表明，两种双链体均形成稳定的右手螺旋双链体，糖基键呈反式构象且为沃森-克里克配对。核Overhauser效应相关光谱（NOESY）和同核化学位移相关谱（COSY）使我们能够确定α和β脱氧核糖采用3'-外向构象。
