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.

supplied as a solution in 20 mM HEPES buffer, pH 7.9, with 0.1 mM EDTA, 2 mM DTT, 12.5 mM MgCl2, ~130 mM KCl, and 20% (w/v) glycerol.