title: NMR analyses on the molecular mechanism of the conformational rigidity of 2-thioribothymidine, a modified nucleoside in extreme thermophile tRNAs.
abstract: 1H-NMR analyses have been made on the conformations of 2-thioribothymidine (s2T), 2-thiodeoxyribothymidine (s2dT), as well as ribothymidine (T) and deoxyribothymidine (dT). s2T and s2dT exclusively take the anti form rather than the syn form. The C3'-endo-gg form of the sugar moiety is remarkably stabilized on modification of T to s2T, but not on modification of dT to s2dT. The steric effects of the 2-thiocarbonyl group and the 2'-hydroxyl group cause the rigidity of the C3'-endo-gg form of s2T. Such rigidity of s2T probably contributes to the thermostability of 2-thiopyrimidine polyribonucleotides and extreme thermophile tRNAs.
mesh_terms: D005051:Eubacterium / Q000378:metabolism; D006358:Hot Temperature; D009682:Magnetic Resonance Spectroscopy; D009690:Nucleic Acid Conformation; D012329:RNA, Bacterial; D012343:RNA, Transfer; D013329:Structure-Activity Relationship; D013891:Thiouridine / Q000031:analogs & derivatives*
chemical_list: D012329:RNA, Bacterial; D013891:Thiouridine; C022856:2-thioribothymidine; D012343:RNA, Transfer