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Your query returned 1 entry. 
Printable version
| EC | 4.6.1.20 | ||||||||
| Accepted name: | ribonuclease U2 | ||||||||
| Reaction: | (1) [RNA] containing adenosine + H2O = an [RNA fragment]-3′-adenosine-3′-phosphate + a 5′-hydroxy-ribonucleotide-3′-[RNA fragment] (overall reaction) (1a) [RNA] containing adenosine = an [RNA fragment]-3′-adenosine-2′,3′-cyclophosphate + a 5′-hydroxy-ribonucleotide-3′-[RNA fragment] (1b) an [RNA fragment]-3′-adenosine-2′,3′-cyclophosphate + H2O = an [RNA fragment]-3′-adenosine -3′-phosphate (2) [RNA] containing guanosine + H2O = an [RNA fragment]-3′-guanosine-3′-phosphate + a 5′-hydroxy-ribonucleotide-3′-[RNA fragment] (overall reaction) (2a) [RNA] containing guanosine = an [RNA fragment]-3′-guanosine-2′,3′-cyclophosphate + a 5′-hydroxy-ribonucleotide-3′-[RNA fragment] (2b) an [RNA fragment]-3′-guanosine-2′,3′-cyclophosphate + H2O = an [RNA fragment]-3′- guanosine-3′-phosphate |
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| Other name(s): | purine specific endoribonuclease; ribonuclease U3; RNase U3; RNase U2; purine-specific ribonuclease; purine-specific RNase; Pleospora RNase; Trichoderma koningi RNase III; ribonuclease (purine) | ||||||||
| Systematic name: | [RNA]-purine 5′-hydroxy-ribonucleotide-3′-[RNA fragment]-lyase (cyclicizing; [RNA fragment]-3′-purine-nucleoside -2′,3′-cyclophosphate-forming and hydrolysing) | ||||||||
| Comments: | The enzyme secreted by the fungus Ustilago sphaerogena cleaves at the 3′-phosphate group of purines, and catalyses 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 hydrolyses 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. | ||||||||
| Links to other databases: | BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 37205-57-5 | ||||||||
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