Lumazine synthase (EC 2.5.1.78, 6,7-dimethyl-8-ribityllumazine synthase, 6,7-dimethyl-8-ribityllumazine synthase 2, 6,7-dimethyl-8-ribityllumazine synthase 1, lumazine synthase 2, lumazine synthase 1, type I lumazine synthase, type II lumazine synthase, RIB4, MJ0303, RibH, Pbls, MbtLS, RibH1 protein, RibH2 protein, RibH1, RibH2) is an enzyme with systematic name 5-amino-6-(D-ribitylamino)uracil butanedionetransferase.[1] This enzyme catalyses the following chemical reaction
6,7-dimethyl-8-ribityllumazine synthase | |||||||||
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Identifiers | |||||||||
EC no. | 2.5.1.78 | ||||||||
Databases | |||||||||
IntEnz | IntEnz view | ||||||||
BRENDA | BRENDA entry | ||||||||
ExPASy | NiceZyme view | ||||||||
KEGG | KEGG entry | ||||||||
MetaCyc | metabolic pathway | ||||||||
PRIAM | profile | ||||||||
PDB structures | RCSB PDB PDBe PDBsum | ||||||||
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This reaction is part of the biosynthesis of riboflavin (vitamin B2). Lumazine synthase is thus found in those organisms (plants, fungi and most microorganisms) which produce riboflavin.[2]
Depending on the species, 5, 10 or 60 copies of the enzyme bind together to form homomers. In the case of 60 copies, the enzyme units form a icosahedral hollow cage. In some bacteria, this cage contains another enzyme involved in the riboflavin synthesis, riboflavin synthase.[2]
These icosahedral cages have been investigated for use in drug delivery or as vaccines, delivering antigens.[2] Using directed evolution, Lumazine synthase has been modified so that it forms larger cages that preferentially package RNA molecules that code for the protein, akin to a virus capsid.[3]