Ribonuclease T2 (RNase T2) is an endoribonuclease that catalyzes the two-stage endonucleolytic cleavage to nucleoside 3'-phosphates and 3'-phosphooligonucleotides terminating in guanylic 3'-phosphate with 2',3'-cyclic phosphate intermediates. RNase T2 was derived from Aspergillus oryzae and dissolved in a solution of 15 mM Na-acetate pH 4.5, 100 mM NaCI, and 50% glycerol.