IUBMB Enzyme Nomenclature


Accepted name: ribonuclease T2

Reaction: RNA + H2O = an [RNA fragment]-3'-nucleoside-3'-phosphate + a 5'-hydroxy-ribonucleotide-3'-[RNA fragment] (overall reaction)
(1a) RNA = an [RNA fragment]-3'-nucleoside-2',3'-cyclophosphate + a 5'-hydroxy-ribonucleotide-3'-[RNA fragment]
(1b) an [RNA fragment]-3'-nucleoside-2',3'-cyclophosphate + H2O = an [RNA fragment]-3'-nucleoside-3'-phosphate

Other name(s): ribonuclease II; base-non-specific ribonuclease; nonbase-specific RNase; RNase (non-base specific); non-base specific ribonuclease; nonspecific RNase; RNase Ms; RNase M; RNase II; Escherichia coli ribonuclease II; ribonucleate nucleotido-2'-transferase (cyclizing); acid ribonuclease; RNAase CL; Escherichia coli ribonuclease I' ribonuclease PP2; ribonuclease N2; ribonuclease M; acid RNase; ribonnuclease (non-base specific); ribonuclease (non-base specific); RNase T2; ribonuclease PP3; ribonucleate 3'-oligonucleotide hydrolase; ribonuclease U4

Systematic name: [RNA] 5'-hydroxy-ribonucleotide-3'-[RNA fragment]-lyase (cyclicizing; [RNA fragment]-3'- nucleoside-2',3'-cyclophosphate-forming and hydrolysing)

Comments: A widely distributed family of related enzymes found in protozoans, plants, bacteria, animals and viruses that cleave ssRNA 3'-phosphate group with little base specificity. The enzyme catalyses a two-stage endonucleolytic cleavage. The first reaction produces 5'-hydroxy-phosphooligonucletides and 3'-phosphooligonucleotides ending with a 2',3'-cyclic phosphodiester, which are released from the enzyme. The enzyme then hydrolyses the cyclic products in a second reaction that takes place only when all the susceptible 3',5'-phosphodiester bonds have been cyclised. The second reaction is a reversal of the first reaction using the hydroxyl group of water instead of the 5'-hydroxyl group of ribose. The overall process is that of a phosphorus-oxygen lyase followed by hydrolysis to form the 3'-nucleotides.

Links to other databases: BRENDA, EXPASY, GTD, KEGG, MetaCyc, CAS registry number:


1. Garcia-Segura, J.M., Orozco, M.M., Fominaya, J.M. and Gavilanes, J.G. Purification, molecular and enzymic characterization of an acid RNase from the insect Ceratitis capitata. Eur. J. Biochem. 158 (1986) 367-372. [PMID: 3732273]

2. Heppel, L.A. Pig liver nuclei ribonuclease. In: Cantoni, G.L. and Davies, D.R. (Eds), Procedures in Nucleic Acid Research, Procedures in Nucleic Acid Research, New York, 1966, pp. 31-36.

3. Reddi, K.K. and Mauser, L.J. Studies on the formation of tobacco mosaic virus ribonucleic acid. VI. Mode of degradation of host ribonucleic acid to ribonucleosides and their conversion to ribonucleoside 5'-phosphates. Proc. Natl. Acad. Sci. USA 53 (1965) 607-613. [PMID: 14338240]

4. Uchida, I. and Egami, F. The specificity of ribonuclease T2. J. Biochem. (Tokyo) 61 (1967) 44-53. [PMID: 6048969]

5. Irie, M. and Ohgi, K. Ribonuclease T2. Methods Enzymol. 341 (2001) 42-55. [PMID: 11582795]

6. Luhtala, N. and Parker, R. T2 Family ribonucleases: ancient enzymes with diverse roles. Trends Biochem. Sci. 35 (2010) 253-259. [PMID: 20189811]

[EC created 1972 as EC, transferred 1978 to EC, modified 1981, transferred 2018 to EC]

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