Abstract: Composition and methods of production of the compound P.sup.1 -adenosine, P.sup.2 -(3' nucleotide monophosphate)-5' pyrophosphate (AppNp) are disclosed. AppNp is useful in the synthesis of a predetermined sequence of RNA using the enzyme T4 RNA ligase. The use of this invention in the field of recombinant DNA will greatly enhance the ability to synthesize genes of known composition.