Ribonuclease T1 (RNase T1) from Aspergillus oryzae is an endoribonuclease that hydrolyzes after G residues. Cleavage occurs between the 3′-phosphate group of a guanidine ribonucleotide and 5′-hydroxyl of the adjacent nucleotide. The initial product is a 2′:3′ cyclic phosphate nucleoside that is hydrolyzed to the corresponding 3′-nucleoside phosphate. It differs from Pancreatic RNase in that it attacks the guanine sites specifically to yield 3′-GMP and oligonucleotides with a 3′-GMP terminal group.
