Ribonuclease H (RNase H) is an endoribonuclease that specifically degrades RNA-DNA hybrids of RNA strands, producing 5´ phosphate-terminated oligoribonucleotides and single-stranded DNA.

Applications
Removal of mRNA during second-strand cDNA synthesis. Removal of poly(A) sequences from mRNA in the presence of Oligo(dT). Oligodeoxynucleotide-mediated RNA cleavage.

Source
Purified from E. coli expressing the E. coli RNase H gene on a plasmid.

Performance and Quality Testing
Ribonucleases, non-specific endodeoxyribonucleases, 3´ and 5´ exodeoxyribonucleases.

Unit Definition
One unit of enzyme can convert ³H labeled poly(A)poly( at 37°C in 20 minutes 1 nmol of RNA in dT) is hydrolyzed to acid-soluble material.

Unit reaction conditions
20 mM Tris-HCl (pH 7.5), 0.1M KCl, 10 mM MgCl₂, 0.1 mM DTT, 5% (w/v) sucrose, 0.5 nmol ³H-labeled poly(A)poly(dT) and 50 µL enzyme, 37°C for 20 min.