Institute of Bioorganic Chemistry, Polish Academy of Sciences, 61-704, Poznan, Noskowskiego 12/14, Poland.
Sci Rep. 2019 Mar 13;9(1):4385. doi: 10.1038/s41598-019-40715-2.
Thionucleotides, especially 4-thiouridine and 6-thioguanosine, are photosensitive molecules that photocrosslink to both proteins and nucleic acids, and this feature is a major reason for their application in various investigations. To get insight into the thermodynamic and structural contributions of 6-thioguanosine to the properties of RNA duplexes a systematic study was performed. In a series of RNA duplexes, selected guanosine residues located in G-C base pairs, mismatches (G-G, G-U, and G-A), or 5' and 3'-dangling ends were replaced with 6-thioguanosine. Generally, the presence of 6-thioguanosine diminishes the thermodynamic stability of RNA duplexes. This effect depends on its position within duplexes and the sequence of adjacent base pairs. However, when placed at a dangling end a 6-thioguanosine residue actually exerts a weak stabilizing effect. Furthermore, the structural effect of 6-thioguanosine substitution appears to be minimal based on NMR and Circular Dichroism (CD) data.
硫代核苷酸，特别是 4-硫尿苷和 6-硫代鸟苷，是光敏分子，可与蛋白质和核酸光交联，这一特性是它们在各种研究中应用的主要原因。为了深入了解 6-硫代鸟苷对 RNA 双链体性质的热力学和结构贡献，进行了系统研究。在一系列 RNA 双链体中，选择位于 G-C 碱基对、错配（G-G、G-U 和 G-A）或 5'和 3'-悬垂末端的鸟嘌呤残基被 6-硫代鸟苷取代。一般来说，6-硫代鸟苷的存在会降低 RNA 双链体的热力学稳定性。这种效应取决于其在双链体中的位置和相邻碱基对的序列。然而，当位于悬垂末端时，6-硫代鸟苷残基实际上会产生微弱的稳定作用。此外，基于 NMR 和圆二色性 (CD) 数据，6-硫代鸟苷取代的结构效应似乎很小。
