Overview for MACiE Entry M0247
EC Number: 22.214.171.124 (A member of the Transferases, Transferring alkyl or aryl groups, other than methyl groups, Transferring alkyl or aryl groups, other than methyl groups (only sub-subclass identified to date))
Enzyme Name: riboflavin synthase
Biological Species: Schizosaccharomyces pombe (Fission yeast)
Catalytic Chain UniprotKB Accession Codes:
- Q9Y7P0 - Riboflavin synthase alpha chain
Representative PDB Code: 1kzl - RIBOFLAVIN SYNTHASE FROM S.POMBE BOUND TOCARBOXYETHYLLUMAZINE (Resolution = 2.10 Å).
Catalytic CATH Codes:
- 126.96.36.199 - Elongation Factor Tu (Ef-tu); domain 3
Display structure information
Overall Comment: This mechanism is not yet fully characterised, and the roles of the various amino acid residues are still very putative.
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Stepwise Description of the Reaction
|Step 1||His102 deprotonates the 7 position methyl group of the first substrate molecule in an initial activation step.|
|Step 2||Cys48 initiates a nucleophilic attack on the second substrate in an addition reaction with the concomitant deprotonation of solvent water.|
|Step 3||The oxyanion of the first activated substrate collapses, initiating a nucleophilic attack on the second activate substrate with concomitant deprotonation of His102.|
|Step 4||His102 deprotonates the intermediate, initiating a double bond rearrangement, re-forming the oxyanion.|
|Step 5||The intermediate tautomerises.|
|Step 6||Water deprotonates the amine with concomitant double bond rearrangement which initiates a nucleophilic attack on the carbon to which the Cys48 is covalently attached in a substitution reaction.|
|Step 7||The oxyanion collapses, initiating double bond rearrangement that results in the cleavage of the C-N bond in an intramolecular elimination with concomitant deprotonation of His102.|
|Step 8||Cys48 deprotonates the ring CH2 group, initiating an elimination reaction, which liberates the reaction products with concomitant deprotonation of Cys48.|
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Catalytic Residues Involved
||Location of Function
- M. Fischer et al. (2005), Nat. Prod. Rep., 22, 324-350. Biosynthesis of flavocoenzymes.
- Y.-J. Zheng et al. (2003), Bioorg. Chem., 31, 278-287. Examination of a reaction intermediate in the active site of riboflavin synthase.
- M. Fischer et al. (2008), Arch. Biochem. Biophys., 474, 252-265. Biosynthesis of vitamin B2: Structure and mechanism of riboflavin synthase.
Homologue information for M0247 (1kzl)
MACiE Homologues (within the PDB)
MACiE Homologues (within UniprotKB/SwissProt)
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