ENZYME entry: EC 18.104.22.168
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3'-(RNA fragment)-lyase (cyclicizing; (RNA fragment)-3'-adenosine-
2',3'-cyclophosphate-forming and hydrolyzing).|
|A 28S rRNA containing guanosine-adenosine pair + H(2)O <=> an (RNA fragment)-3'-adenosine-3'-phosphate + a 5'-a hydroxy-guanosine-3'-(RNA fragment)|
- Ribotoxins are rRNA endonucleases that catalyze the cleavage of the
phosphodiester bond between guanosine and adenosine residues at one
specific position in 28S rRNA.
- The enzyme secreted by Aspergillus giganteus specifically cleaves rat
28S rRNA between G(4325) and A(4326) and displays cytotoxic activity
toward animal cells.
- It can also act on bacterial rRNAs.
- The enzyme catalyzes a two-stage endonucleolytic cleavage.
- The first reaction produces 5'-hydroxy-phosphooligonucletides and
3'-phosphooligonucleotides ending 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.
|PRIAM enzyme-specific profiles||22.214.171.124|
|KEGG Ligand Database for Enzyme Nomenclature||126.96.36.199|
|IUBMB Enzyme Nomenclature||188.8.131.52|
|MEDLINE||Find literature relating to 184.108.40.206|
|Rhea expert-curated reactions||220.127.116.11|
entries corresponding to 4.6.1.-
All ENZYME / UniProtKB/Swiss-Prot entries corresponding to 4.6.-.-
All ENZYME / UniProtKB/Swiss-Prot entries corresponding to 4.-.-.-