Andre A, Guschlbauer W
Nucleic Acids Res. 1974 Jun;1(6):803-7. doi: 10.1093/nar/1.6.803.
The flexibility of pyrimidine nucleosides has been investigated by measuring their circular dichroism in hydroalcoholic solutions over a large temperature range (-100 degrees to +40 degrees C). It was observed that ss-Uridine (Urd) and ss-Cytidine (Cyd) showed a decrease of the main dichroic band of about 40 percent, while sterically hindered nucleosides (alphaUrd, ara-Uracile, 02-2' anhy-dro-Urd, 2'3'-0-isopropylidene-Urd) showed only small decreases. It is concluded that the flexibility of the glycosidic linkage in conjunction with the pseudo-rotation of the sugar residue is responsible for these changes; the thermodynamic values which can be deduced from these decreases are compatible with an oscillatory motion around the glycosidic bond, but exclude anti-syn transformations in pyrimidine nucleosides.
通过在较大温度范围(-100℃至+40℃)的水醇溶液中测量嘧啶核苷的圆二色性,研究了其灵活性。观察到单链尿苷(Urd)和单链胞苷(Cyd)的主要二色性带下降了约40%,而空间位阻核苷(αUrd、阿糖胞苷、02-2'脱水尿苷、2'3'-O-异丙叉尿苷)仅显示出小幅度下降。得出的结论是,糖苷键的灵活性与糖残基的假旋转共同导致了这些变化;从这些下降中推导得出的热力学值与围绕糖苷键的振荡运动相符,但排除了嘧啶核苷中的反式-顺式转变。