Merck, R4875-5G, Ribonuclease A from bovine pancreas

RNase A, Ribonuclease A, is an endoribonuclease that cleaves the phosphodiester bonds of single strand RNA after pyrimidine nucleotides. It attacks at the 3′ phosphate end (For example pG-pG-pC-pA-pG will be cleaved to give pG-pG-pCp and A-pG). The highest activity is exhibited with single stranded RNA. RNase A is a single chain polypeptide containing 4 disulfide bridges. In contrast to RNase B, it is not a glycoprotein. Ribonucleases do not hydrolyze DNA, because the DNA lacks 2′-OH groups essential for the formation of cyclic intermediates. RNase A can also hydrolyze RNA from protein samples. RNase A can be inhibited by alkylation of His12 and His119 and activated by potassium and sodium salts. RNAse is inhibited in the presence of heavy metal ions. RNase is also inhibited competitively by DNA.