Polynucleotide phosphorylase (PNPase) is a bifunctional enzyme with a phosphorolytic 3' to 5' exoribonuclease activity and a 3'-terminal oligonucleotide polymerase activity. It is also involved in mRNA processing and degradation in bacteria, plants, and humans.http://www.creative-enzymes.com/product/Polynucleotide-Phosphorylase-From-Synechocystis-Sp-Recombinant_1405.html