Yokoyama S, Yamaizumi Z, Nishimura S, Miyazawa T
Nucleic Acids Res. 1979 Jun 11;6(7):2611-26. doi: 10.1093/nar/6.7.2611.
The molecular conformations of naturally occurring 2-thiopyrimidine nucleosides (5-methylaminomethyl-2-thiouridine, 5-methoxycarbonylmethyl-2-thiouridine and 2-thiocytidine) and 5'-mononucleotides (5-methylaminomethyl-2-thiouridine 5'-monophosphate and 2-thiocytidine 5'-monophosphate) in 2H2O solution were elucidated by analyses of the proton NMR spin-coupling constant, nuclear Overhauser effect, and lanthanide-induced shifts and relaxation enhancements. As monomers, these nucleotides are almost exclusively in the 3E-gg-anti form, even in the absence of ordinary stabilizing factors of this form; i. e., base-stacking and base-pairing interactions with other nucleotide units. This inherent conformational rigidity of the 2-thiopyrimidine units probably contributes to stability of the conformation of tRNA.
通过对质子核磁共振自旋耦合常数、核Overhauser效应、镧系元素诱导位移和弛豫增强的分析，阐明了天然存在的2-硫代嘧啶核苷（5-甲基氨基甲基-2-硫代尿苷、5-甲氧基羰基甲基-2-硫代尿苷和2-硫代胞苷）以及5'-单核苷酸（5-甲基氨基甲基-2-硫代尿苷5'-单磷酸和2-硫代胞苷5'-单磷酸）在2H2O溶液中的分子构象。作为单体，这些核苷酸几乎完全处于3E-gg-反式构象，即使在缺乏这种构象的常见稳定因素（即与其他核苷酸单元的碱基堆积和碱基配对相互作用）的情况下也是如此。2-硫代嘧啶单元这种固有的构象刚性可能有助于tRNA构象的稳定性。
