Synthesis of TMG-capped RNA-DNA chimeric oligonucleotides

This paper deals with the synthesis of m(3)(2,2.7)G(5')pppAmpUmpApd(CpTpTpApCpCpT), a 5'-TMG-capped RNA-DNA chimeric oligonucleotide, which is expected to be conveyed to the nucleus by snurportin 1, a nuclear-transport protein. This 5'-TMG-capped RNA-DNA chimeric molecule was synthesized by the enzymatic condensation Of M(3)(2,2,7)G(5')pppAmpUmpA with A(5')ppd(CpTpTpApCpCpT) in the presence of RNA ligase. An inherent serious side reaction was disclosed in the 5'-adenylation of d(CpTpTpApCpCpT) on the solid support, but the use of an active ester intermediate as the pA donor gave an improved result. (C) 2003 Published by Elsevier Science Ltd.