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ENZYME

ENZYME entry: EC 4.2.1.168

PURL: https://purl.expasy.org/enzyme/EC/4.2.1.168
Accepted Name
GDP-4-dehydro-6-deoxy-alpha-D-mannose 3-dehydratase
Reaction catalysed
GDP-4-dehydro-alpha-D-rhamnose + L-glutamate = GDP-4-dehydro-3,6-dideoxy-alpha-D-mannose + 2-oxoglutarate + NH4(+)
Comment(s)
  • This enzyme, involved in beta-L-colitose biosynthesis, is a unique vitamin-B6-dependent enzyme.
  • In the first step of catalysis, the bound pyridoxal phosphate (PLP) cafactor is transaminated to the pyridoxamine 5'-phosphate (PMP) form of vitamin B6, using L-glutamate as the amino group donor.
  • The PMP cofactor then forms a Schiff base with the sugar substrate and the resulting adduct undergoes a 1,4-dehydration to eliminate the 3-OH group.
  • Hydrolysis of the product from the enzyme restores the PLP cofactor and results in the release of an unstable enamine intermediate.
  • This intermediate tautomerizes to form an imine form, which hydrolyzes spontaneously, releasing ammonia and forming the final product.
Cross-references
BRENDA4.2.1.168
EC2PDB4.2.1.168
ExplorEnz4.2.1.168
KEGG Ligand Database for Enzyme Nomenclature4.2.1.168
IUBMB Enzyme Nomenclature4.2.1.168
MEDLINEFind literature relating to 4.2.1.168
MetaCyc4.2.1.168
Rhea expert-curated reactions4.2.1.168
UniProtKB/Swiss-Prot
D3QY10, COLD_ECOCBG4WJD4, COLD_YERPU

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