Combining recombinant ribonuclease U2 and protein phosphatase for RNA modification mapping by liquid chromatography-mass spectrometry.

Ribonuclease (RNase) mapping of modified nucleosides onto RNA sequences is limited by RNase availability. A codon-optimized gene for RNase U2, a purine selective RNase with preference for adenosine, has been designed for overexpression using Escherichia coli as the host. Optimal expression conditions were identified enabling generation of milligram-scale quantities of active RNase U2.