James J K, Tinoco I
Department of Chemistry, University of California, Berkeley 94720.
Nucleic Acids Res. 1993 Jul 11;21(14):3287-93. doi: 10.1093/nar/21.14.3287.
The solution structure of the DNA analogue of the unusually stable r[C(UUCG)G] RNA hairpin, 5'-d[GGA-C(TTCG)GTCC]-3', has been determined by NMR spectroscopy, and its structure has been compared to that of the RNA molecule. The RNA molecule is compact and rigid with a highly structured loop. However, the DNA molecule is much less structured. The DNA hairpin contains a B-form stem of four base pairs. The terminal base pair frays, and the 3'-terminal nucleotides, C11 and C12, are in equilibrium between 2'-endo and 3'-endo conformations. Unlike the RNA loop, the DNA loop contains no syn nucleotides, and there is no evidence for base-base or base-phosphate hydrogen bonding in the loop. The loop is flexible, and reveals no specific internucleotide interactions.
异常稳定的r[C(UUCG)G] RNA发夹的DNA类似物5'-d[GGA-C(TTCG)GTCC]-3'的溶液结构已通过核磁共振光谱法确定，并将其结构与RNA分子的结构进行了比较。RNA分子紧凑且刚性，具有高度结构化的环。然而，DNA分子的结构则少得多。DNA发夹包含一个由四个碱基对组成的B型茎。末端碱基对发生解链，3'-末端核苷酸C11和C12处于2'-内型和3'-内型构象之间的平衡状态。与RNA环不同，DNA环不包含顺式核苷酸，并且没有证据表明环内存在碱基-碱基或碱基-磷酸氢键。该环是灵活的，未显示出特定的核苷酸间相互作用。
