The synthesis and properties of oligoribonucleotide-spermine conjugates.

Polyamines stabilise nucleic acids against chemical and enzymatic degradation, facilitate the formation of secondary and tertiary structures and enhance cellular uptake. Therefore methods for the syntheses of polyamine-nucleic acid conjugates are of interest. A route for the syntheses of RNA-spermine conjugates has been developed. The polyamine was introduced to the C-5 position of uridine via an ethyl tether and the molecule elaborated into a synthon suitable for oligoribonucleotide assembly. The resultant oligomers were components of the hairpin ribozyme. Characterisation of the spermine-conjugated catalytic RNA revealed that attachment of the polyamine was well tolerated in three of four positions, namely U41, U37 and U34, suggesting that conjugation to C-5 brings about minimal structural perturbation.