ExplorEnz: EC 4.6.1.18

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4.6.1.18

Accepted name:

pancreatic ribonuclease

Reaction:

(1) an [RNA] containing cytidine + H₂O = an [RNA]-3′-cytidine-3′-phosphate + a 5′-hydroxy-ribonucleotide-3′-[RNA] (overall reaction)
(1a) an [RNA] containing cytidine = an [RNA]-3′-cytidine-2′,3′-cyclophosphate + a 5′-hydroxy-ribonucleotide-3′-[RNA]
(1b) an [RNA]-3′-cytidine-2′,3′-cyclophosphate + H₂O = an [RNA]-3′-cytidine-3′-phosphate
(2) an [RNA] containing uridine + H₂O = an [RNA]-3′-uridine-3′-phosphate + a 5′-hydroxy-ribonucleotide-3′-[RNA]
(2a) an [RNA] containing uridine = an [RNA]-3′-uridine-2′,3′-cyclophosphate + a 5′-hydroxy-ribonucleotide-3′-[RNA]
(2b) an [RNA]-3′-uridine-2′,3′-cyclophosphate + H₂O = an [RNA]-3′-uridine-3′-phosphate

Other name(s):

RNase; RNase I; RNase A; pancreatic RNase; ribonuclease I; endoribonuclease I; ribonucleic phosphatase; alkaline ribonuclease; ribonuclease; gene S glycoproteins; Ceratitis capitata alkaline ribonuclease; SLSG glycoproteins; gene S locus-specific glycoproteins; S-genotype-asssocd. glycoproteins; ribonucleate 3′-pyrimidino-oligonucleotidohydrolase

Systematic name:

RNA lyase ([RNA]-3′-cytidine/uridine-3′-phosphate and 5′-hydroxy-ribonucleotide-3′-[RNA] producing)

Comments:

Specifically cleaves at the 3′-side of pyrimidine (uracil or cytosine) phosphate bonds in RNA. The reaction takes place in two steps, with the 2′,3′-cyclic phosphodiester intermediates released from the enzyme at the completion of the first step. Hydrolysis of these cyclic compounds occurs at a much slower rate through a reversal of the first step, in which the -OH group of water substitutes for the 2′-OH group of the ribose used in the first step, and does not take place until essentially all the susceptible 3′,5′-phosphodiester bonds have been cyclised. The enzyme can act as an endo- or exo ribonuclease.

Links to other databases:

BRENDA, EXPASY, GTD, KEGG, MetaCyc, PDB, CAS registry number: 9001-99-4

References:

1.	Anfinsen, C.B. and White, F.H., Jr. The ribonucleases: occurrence, structure, and properties. In: Boyer, P.D., Lardy, H. and Myrbäck, K. (Ed.), The Enzymes, 2nd edn, vol. 5, Academic Press, New York, 1961, pp. 95–122.
2.	Beard, J.R. and Razzell, W.E. Purification of alkaline ribonuclease II from mitochondrial and soluble fractions of liver. J. Biol. Chem. 239 (1964) 4186–4193. [PMID: 14247667]
3.	Cannistraro, V.J. and Kennell, D. Purification and characterization of ribonuclease M and mRNA degradation in Escherichia coli. Int. J. Biochem. 181 (1989) 363–370. [DOI] [PMID: 2653829]
4.	Cuchillo, C.M., Pares, X., Guasch, A., Barman, T., Travers, F. and Nogues, M.V. The role of 2′,3′-cyclic phosphodiesters in the bovine pancreatic ribonuclease A catalysed cleavage of RNA: intermediates or products. FEBS Lett. 333 (1993) 207–210. [PMID: 7693511]
5.	Loverix, S., Laus, G., Martins, J.C., Wyns, L. and Steyaert, J. Reconsidering the energetics of ribonuclease catalysed RNA hydrolysis. Eur. J. Biochem. 257 (1998) 286–290. [PMID: 9799130]

[EC 4.6.1.18 created 1972 as EC 3.1.4.22, transferred 1978 to EC 3.1.27.5, modified 1981, transferred 2018 to EC 4.6.1.18]