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ENZYME entry: EC

Accepted Name
ribonuclease U2
Alternative Name(s)
RNase U2
Reaction catalysed
  • [RNA] containing adenosine + H2O <=> an [RNA fragment]-3'-adenosine-3'-phosphate + a 5'-hydroxy-ribonucleotide-3'-[RNA fragment]
  • [RNA] containing guanosine + H2O <=> an [RNA fragment]-3'-guanosine-3'-phosphate + a 5'-hydroxy-ribonucleotide-3'-[RNA fragment]
  • The enzyme secreted by the fungus Ustilago sphaerogena cleaves at the 3'-phosphate group of purines, and catalyzes a two-stage endonucleolytic cleavage.
  • The first reaction produces 5'-hydroxy-phosphooligonucletides and 3'-phosphooligonucleotides ending in Ap or Gp 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
PRIAM enzyme-specific profiles4.6.1.20
KEGG Ligand Database for Enzyme Nomenclature4.6.1.20
IUBMB Enzyme Nomenclature4.6.1.20
MEDLINEFind literature relating to
Rhea expert-curated reactions4.6.1.20
P00654, RNU2_USTSP

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