RNase I degrades single-stranded RNA to nucleoside 3´ monophosphates via 2´,3´ cyclic monophosphate intermediates by cleaving between all dinucleotide pairs,2,3 unlike RNase A, which cleaves only after cytosine and uridine. In addition, the enzyme is completely inactivated by heating at 70°C for 15 minutes, eliminating the requirement to remove the enzyme prior to many subsequent procedures.