Synthesis and Application of New Modified Dinucleotide Cap Analog

We describe synthesis of a chain-terminating mRNA cap dinucleotide m2 7, 2'OG[5']ppp[5']m7G analog. A new dinucleotide cap analog was synthesized with methyl groups on the both N7 guanine moieties, as well as the 2'-OH of one of the ribose moiety is reported. The biological validation of triple methylated cap analog was done with respect to their effects on capping efficiency, yield of RNAs during in vitro transcription, and the translational activity of these RNAs upon transfection into HeLa cells. The RNA capped with the trimethylated analog (m2 7,2'OG[5']ppp[5']m7G) was translated the most efficiently, with ∼ 2.5 -fold more activity than the conventional cap (m7G[5']ppp[5']G).