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ENZYME entry: EC 4.6.1.21

Accepted Name
Enterobacter ribonuclease.
Alternative Name(s)
(RNA)-adenosine-cytidine 5'-hydroxy-adenosoine ribonucleotide-3'-(RNA fragment)-lyase (cyclicizing; (RNA fragment)-3'-cytidine- 2',3'-cyclophosphate-forming and hydrolyzing).
Reaction catalysed
RNA containing adenosine-cytidine + H(2)O <=> an (RNA fragment)-3'-cytidine-3'-phosphate + a 5'-a hydroxy-adenosine -3'-(RNA fragment)
Comment(s)
  • Preference for cleavage at Cp-A bonds.
  • Homopolymers of A, U or G are not hydrolyzed.
  • CpG bonds are hydrolyzed less well and there is no detectable hydrolysis between two purines or two pyrimidines.
  • The enzyme catalyzes a two-stage endonucleolytic cleavage.
  • The first reaction produces 5'-hydroxy-phosphooligonucletides and 3'-phosphooligonucleotides ending a with 2',3'-cyclic phosphodiester, which are released from the enzyme.
  • The enzyme then hydrolyzes these cyclic compounds 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.
  • Formerly EC 3.1.27.6.
Cross-references
PROSITEPDOC00459
BRENDA4.6.1.21
EC2PDB4.6.1.21
ExplorEnz4.6.1.21
PRIAM enzyme-specific profiles4.6.1.21
KEGG Ligand Database for Enzyme Nomenclature4.6.1.21
IUBMB Enzyme Nomenclature4.6.1.21
IntEnz4.6.1.21
MEDLINEFind literature relating to 4.6.1.21
MetaCyc4.6.1.21
UniProtKB/Swiss-Prot
P21338, RNI_ECOLI

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