Ternary conjugates of guanosine monophosphate as initiator nucleotides for the enzymatic synthesis of 5'-modified RNAs.

We give a detailed account on the enzymatic synthesis of RNA conjugates by T7 RNA polymerase using modified initiator nucleotides during transcription. Following two different routes, ternary conjugates of guanosine-5'-monophosphate, poly(ethylene glycol), and anthracene were synthesized via phosphoramidite intermediates and characterized by a variety of spectroscopic techniques. Up to a degree of polymerization nPEG of about 17, these conjugates were efficiently incorporated into RNA by T7 RNA polymerase at the 5'-termini, thereby giving access to RNA conjugates required for biochemical studies as well as for the exploration of the catalytic potential of ribonucleic acids. The resulting conjugates are intact and functional.