Synthesis of Oligoribonucleotides Containing 2-Thiouridine: Incorporation of 2-Thiouridine Phosphoramidite without Base Protection

摘要

Transfer RNAs are unique among the naturally occurring RNAs in that a very high percentage of the nucleo-sides are chemically modified. With few exceptions, the functional role of these diverse nucleoaides is unknown. The naturally occurring nucleoaide modifications comprise a structurally diverse group, and many simple classes of chemical modifications that one could envisage, particularly with respect to the bases, are represented in nature, One simple base modification among uridine nucleotides that has dramatic effects on nucleoside . conformation is the replacement of oxygen at the C-2 position of the base with sulfur. For 2-thiouridine, it has been shown that sulfur substantially stabilizes the 3'-endo sugar conformation, at the nucleoside and dinucle-otide level, but due to the synthetic difficulties this property has not been confirmed for oligohucleotides.