We have synthesized four different 5′-diphosphorylated oligoribonucleotides, varying in length from 11 to 13 nucleotides by a new solid phase method. After deprotectlon and partial purification the 5′-diphosphorylated oligoribonucleotides could be converted to capped (m7Gppp)-oligoribonucleotides using guanylyl transferase. Radlolabelled capped oligoribonucleotides acted as primers for the influenza A virus RNA polymerase in vitro. The solid phase method described here should also allow the addition of 5′-diphosphates to synthetic ollgodeoxyribonucleotides and be capable of automation.
Bibliographical noteFunding Information:
We thank Prof. G. Lowe for originally suggesting the phosphorylation method and for advice and Dr T. Claridge for the3IP NMR analysis. We acknowledge the encouragement of Drs M. Gait and B. Sproat This work was supported by an MRC project grant to GGB and an NIH grant GM29812 to Prof. J. A. McCloskey (University of Utah).