This invention relates to in vitro production of nucleic acids, particularly RNAs and specifically messenger RNAs (mRNA).

A scalable process for production of polyribonucleotides of controlled molecular weight range through variation of processing time and input concentrations. Key elements include a method for immobilization of polynucleotide phosphorylase which has been covalently attached to an amino-functionalized solid support via a glutaraldehyde linkage; a method of repeatedly reacting inosine diphosphate or cytidine diphosphate monomer s with immobilized polynucleotide phosphorylase to produce polyribonucleotide chains; control of the chain length of Poly(I) and Poly (C) by varying cofactor concentration and the length of reaction time; a method for controlled and efficient large-scale manufacture of a specific, determined range of molecular weight poly I and poly C homopolymer chains.

The present invention provides compositions, kits, and methods for synthesizing polyadenylic acid using polynucleotide phosphorylase, adenosine diphosphate, a buffering agent, and a divalent metal cation. In certain embodiments, the adenosine diphosphate is present at a concentration between about 5.0 mM and about 100 mM, and the buffering agent has a pH around 8.0. In some embodiments, the prepared polyadenylic acid compositions are free of detectable nucleic acid.