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Riboflavin synthase

Riboflavin synthase
Crystal structure.jpg
Crystallographic structure of E. coli
riboflavin synthase.
Identifiers
EC number 2.5.1.9
CAS number 9075-82-5
Databases
IntEnz IntEnz view
BRENDA BRENDA entry
ExPASy NiceZyme view
KEGG KEGG entry
MetaCyc metabolic pathway
PRIAM profile
PDB structures RCSB PDB PDBe PDBsum
Gene Ontology AmiGO / EGO
6,7-dimethyl-8-ribityllumazine synthase
Monomer With Ligands.jpg
Riboflavin synthase from S. pombe bound to carboxyethyllumazine.
Identifiers
Symbol DMRL_synthase
Pfam PF00885
InterPro IPR002180
SCOP 1rvv
SUPERFAMILY 1rvv

Riboflavin synthase is an enzyme that catalyzes the final reaction of riboflavin biosynthesis:

(2) 6,7-dimethyl-8-ribityllumazineriboflavin + 5-amino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione

The Riboflavin synthase monomer is 23kDa. Each monomer contains two beta-barrels and one α-helix at the C-terminus (residues 186-206.) The monomer folds into pseudo two-fold symmetry, predicted by sequence similarity between the N-terminus barrels (residues 4-86) and the C-terminus barrel (residues 101-184). The enzyme from different species adopts different quaternary structures, from monomeric to 60 subunits

Two 6,7-dimethyl-8-ribityllumazine (Lumazine synthase) molecules are hydrogen bound to each monomer as the two domains are topologically similar. The active site is located in the interface of the substrates between monomer pairs and modeled structures of the active site dimer have been created. Only one of the active sites of the enzyme catalyze riboflavin formation at a time as the other two sites face outward and are exposed to solvent. The amino acid residues involved in hydrogen bonding to the ligand are pictured, participating residues may include Thr148, Met160, Ile162, Thr165, Val6, Tyr164, Ser146, and Gly96 at the C-terminal domain and Ser41, Thr50, Gly 62, Ala64, Ser64, Val103, Cys48, His102 at the N-terminal domain.


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Wikipedia

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