Ribonuclease Pancreatic is a secreted enzyme that belongs to the pancreatic ribonuclease family. RNASE1 is an endonuclease that cleaves internal phosphodiester RNA bonds on the 3'-side of pyrimidine bases. RNASE1 prefers poly(C) as a substrate and hydrolyzes 2',3'-cyclic nucleotides, with a pH optimum near 8.0. RNASE1 acts on single stranded and double stranded RNA.