Purified RNase A isolated from bovine pancreas. RNase A is an endoribonuclease that exists as a single chain polypeptide containing 4 disulphide bridges. It can be inhibited by alkylation of the histidine-12 or histidine-119 that are present in the active site. Activators of RNase A include potassium and sodium salts. The optimal conditions for activity are 60°C and pH 7.6.