Ribonuclease T1 has extensive applications in molecular cloning, DNA sequencing, and as a non-mammalian source of RNase in various applications. Because of its specificity it has been a commonly used cleavage enzyme for the determination of structure, nearest neighbor frequencies, and RNA sequencing. The enzyme has further application in the preparation of nucleoside 2',3'-cyclic phosphates, the synthesis of oligonucleotides, and the removal of RNA from DNA preparations.