Biosynthesis of vitamin b2 (riboflavin)

Annu Rev Nutr. 2000;20:153-67. doi: 10.1146/annurev.nutr.20.1.153.


The biosynthesis of one riboflavin molecule requires one molecule of GTP and two molecules of ribulose 5-phosphate as substrates. The imidazole ring of GTP is hydrolytically opened, yielding a 4, 5-diaminopyrimidine which is converted to 5-amino-6-ribitylamino-2, 4(1H,3H)-pyrimidinedione by a sequence of deamination, side chain reduction and dephosphorylation. Condensation of 5-amino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione with 3, 4-dihydroxy-2-butanone 4-phosphate obtained from ribulose 5-phosphate affords 6,7-dimethyl-8-ribityllumazine. Dismutation of the lumazine derivative yields riboflavin and 5-amino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione, which is recycled in the biosynthetic pathway. The structure of the biosynthetic enzyme, 6,7-dimethyl-8-ribityllumazine synthase, has been studied in considerable detail.

Publication types

  • Review

MeSH terms

  • Bacillus subtilis / enzymology
  • Enzymes / chemistry
  • Enzymes / metabolism*
  • Enzymes / physiology
  • Escherichia coli / enzymology
  • GTP Cyclohydrolase / chemistry
  • GTP Cyclohydrolase / isolation & purification
  • GTP Cyclohydrolase / metabolism
  • Humans
  • Riboflavin / biosynthesis*
  • Riboflavin / chemistry
  • Riboflavin / genetics
  • Riboflavin / metabolism
  • Riboflavin Synthase / metabolism*


  • Enzymes
  • Riboflavin Synthase
  • GTP Cyclohydrolase
  • Riboflavin