Bovine Ribonuclease APancreatic ribonuclease (RNase I) catalyzes cleavage of the phosphodiester bond between the 5'-ribose of a nucleotide and the phosphate group attached to the 3'-ribose of an adjacent pyrimidine nucleotide forming a 2',3'-cyclic phosphate which may then be hydrolyzed to the corresponding 3'-nucleoside phosphate. Ribonuclease A has a molecular weight of 13,700 daltons. It operates in an optimum pH range of 7.0-7.5.
Ribonuclease B has a molecular weight of 14,700 300 daltons. It is a glycoprotein which possesses an amino acid composition indistinguishable from that of RNase A. It contains 6 residues of mannose and 2 residues of N-acetylglucosamine per molecule. It is a glycosylated derivative of RNase A.