Ambion™ RNase I efficiently cleaves after all four bases of single-stranded RNA, in contrast to RNase A, which only cleaves after C and U residues. RNase I degrades all RNA dinucleotide bonds leaving a 5' hydroxyl and 2', 3' cyclic monophosphate. Supplied in one tube of 25,000 U (100 U/ μL). RNase I will degrade any RNA to a mixture of mononucleotides, dinucleotides, and trinucleotides and does not degrade DNA, although it will bind to DNA. It has a marked preference for single-stranded RNA over double-stranded RNA, which allows it to work well in ribonuclease protection assays. This RNase I is rigorously tested for nonspecific contaminating endonuclease, exonuclease, and protease activity.

Unit Definition:
One unit is the amount of enzyme required to produce 1 μg of acid-soluble material from mouse liver RNA in 30 min at 37°C.