Synthesis and properties of 2'-O-methyl-2-thiouridine and oligoribonucleotides containing 2'-O-methyl-2-thiouridine.

Abstract A new method for the synthesis of 2′- O -methyl-2-thiouridine (s 2 Um) found in thermophilic bacterial tRNA was developed. Structural properties of s 2 Um and s 2 Um p U were studied by using 1 H NMR spectroscopy. A modified nonaribonucleotide (RNA*: 5′-CGUUs 2 UmUUGC-3′) was synthesized to study the base-recognition ability of s 2 Um in formation of RNA–RNA and RNA–DNA duplexes. The UV melting experiments revealed that RNA*–RNA and RNA*–DNA duplexes having an s 2 U-A base pair are more stable than those having a U-A base pair. On the contrary, the thermal stability of RNA*–RNA and RNA*–DNA duplexes having an s 2 U-G wobble base pair was much lower than that of the unmodified duplexes having a natural U-G base pair. It is concluded that s 2 Um has higher selectivity toward A over G than unmodified U.