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ENZYME entry: EC 4.1.99.23

Accepted Name
5-hydroxybenzimidazole synthase.
Alternative Name(s)
HBI synthase.
Reaction catalysed
5-amino-1-(5-phospho-beta-D-ribosyl)imidazole + S-adenosyl-L-methionine + reduced acceptor <=> 5-hydroxybenzimidazole + 5'-deoxyadenosine + L-methionine + formate + formate + NH(3) + phosphate + oxidized acceptor
Comment(s)
  • The enzyme, purified from bacteria, is part of the anaerobic pathway for cobalamin biosynthesis.
  • It binds a [4Fe-4S] cluster that is coordinated by 3 cysteines and an exchangeable S-adenosyl-L-methionine molecule.
  • The first stage of catalysis is reduction of the S-adenosyl-L- methionine to produce L-methionine and a 5'-deoxyadenosin-5'-yl radical that is crucial for the conversion of the substrate.
Cross-references
BRENDA4.1.99.23
EC2PDB4.1.99.23
ExplorEnz4.1.99.23
PRIAM enzyme-specific profiles4.1.99.23
KEGG Ligand Database for Enzyme Nomenclature4.1.99.23
IUBMB Enzyme Nomenclature4.1.99.23
IntEnz4.1.99.23
MEDLINEFind literature relating to 4.1.99.23
MetaCyc4.1.99.23
UniProtKB/Swiss-Prot
A0A0K1TPY7, BZAA_EUBLI;  Q2RHR4, BZAA_MOOTA;  A0A0K1TQ05, BZAB_EUBLI;  
Q2RHR5, BZAB_MOOTA;  Q1JZW3, BZAF_DESA6;  C0QJ00, BZAF_DESAH;  
Q39YG0, BZAF_GEOMG;  P61425, BZAF_GEOSL;  

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