Synthesis and hybridization studies on two complementary nona(2'-O-methyl)ribonucleotides

Abstract

2′-O-Methyl derivatives of the common ribonucleosides except for guanosine were synthesized via the 2′-O-methylation of appropriately-protected nucleosides with CH₃I in the presence of Ag₂O. The 2′-O-methylguanosine derivative was prepared by the monomethylation of a 2′, 3′-cis-diol system with diazomethane. These derivatives were converted to protected 2′-O-methylribonucleoside 3′-phosphates and used for oligonucleo-tide synthesis on polymer supports. Thus, oligo(2′-O-methyl-ribonucleotides) having the sequence identical to the consensus sequence of the 5′-splice junction CAGGUAAGU and its complement were synthesized in a stepwise manner using the phosphotriester method. Thermal stabilities (Tm′s) of the duplex of these 2′-O-methyl ribo-oligomers and eight related duplexes containing ribo- or deoxyribo-oligomers were examined. It was found that the 2′-O-methyl oligoribonucleotides can be utilized as an alternative to an oligoribonucleotide probe in RNA hybridizations as the hybrid formed has a high, or a higher Tm, the probe is much easier to synthesize and it is less likely to be enzymatically degraded.