title: Biosynthesis of Riboflavin.
abstract: The biosynthesis of riboflavin requires 1 equivalent of GTP and 2 equivalents of ribulose phosphate. The first committed reactions of the convergent pathway are catalyzed by GTP hydrolase II and 3,4-dihydroxy-2-butanone 4-phosphate synthase. The initial reaction steps afford 5-amino-6-ribitylaminopyrimidine 5'-phosphate, which needs to be dephosphorylated by a hitherto elusive hydrolase. The dephosphorylated pyrimidine is condensed with the carbohydrate precursor, 3,4-dihydroxy-2-butanone 4-phosphate. The resulting 6,7-dimethyl-8-ribityllumazine affords riboflavin by a mechanistically unique dismutation, i.e., by formation of a pentacyclic dimer that is subsequently fragmented.
authors.forename: Markus
authors.initials: M
authors.lastname: Fischer
authors.forename: Adelbert
authors.initials: A
authors.lastname: Bacher