Ribonuclease A is an endoribonuclease that cleaves single stranded RNA after pyrimidine nucleotides. It attacks at the 3’ phosphate end. Ribonucleases do not hydrolyze DNA, because the DNA lacks 2'-OH groups essential for the formation of cyclic intermediates. RNase can hydrolyze RNA from protein samples. Pancreatic RNase A specifically cleaves at the 3'-side of pyrimidine (uracil or cytosine) phosphate bonds.http://www.creative-enzymes.com/product/Native-Bovine-Ribonuclease-A_1434.html