http://www.creativebiomart.net/description_382728_12.htm

RNase A, also known as ribonuclease A and RNASE1, is a member of the ribonuclease A superfamily. RNase A cleaves internal phosphodiester RNA bonds on the 3-side of pyrimidine bases. This Cleavage takes place in two steps: first, the 3&rsquo,5’-phosphodiester bond is cleaved to generate a 2&rsquo,3’-cyclic phosphodiester intermediate; second, the cyclic phosphodiester is hydrolyzed to a 3’-monophosphate. RNase A has four disulfide bonds in its native state: Cys26-Cys84, Cys58-110, Cys40-95 and Cys65-72. The first two are essential for conformational folding. The latter two disulfide bonds are less essential for folding; either one can be reduced (but not both) without affecting the native structure under physiological conditions.