Recognition of target chain-length by use of oligonucleotides having bulky substituents at the terminal bases.

We synthesized 2'-O-methyl RNAs having bulky substituents at the 5' and 3'-terminal bases and examined their hybridization properties. The hybridization of the modified RNAs to the targets RNA was studied varying the chain length of the targets. As the result, it was proved that the duplex of the modified 2'-O-methyl RNAs and the long targets were destabilized in comparison with that of the modified 2'-O-methyl RNAs and the short targets. We hope that these oligonucleotides which could recognize the target chain-length would be the simple and convenient tool for the detection of small RNAs such as the microRNAs.