Large-scale synthesis of messenger RNA

A method for large-scale production of a composition enriched for full-length mRNA molecules comprising synthesizing in vitro mRNA using a recombinant SP6 RNA polymerase having 90% identity to SEQ ID NO:

• 1, wherein the mRNA is synthesized in about 1 gram to 250 gram quantities in a single batch in a reaction mixture comprising NTPs at a concentration ranging from 1-10 mM each NTP, a DNA template at a concentration ranging from 0.01-0.5 mg/ml, the recombinant SP6 RNA polymerase at a concentration ranging from 0.01-0.1 mg/ml, and a salt or buffering agent, at pH 6.5-8.0, and wherein the reaction is incubated for 60-120 minutes at between 37° C.−42° C.