Biosynthesis of riboflavin.
The biosynthesis of one riboflavin molecule requires one molecule of GTP and two molecules of ribulose 5-phosphate. The imidazole ring of GTP is hydrolytically opened, yielding a 4,5-diaminopyrimidine that 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. Two reaction steps in the biosynthetic pathway catalyzed by 3,4-dihydroxy-2-butanone 4-phosphate synthase and riboflavin synthase are mechanistically very complex. The enzymes of the riboflavin pathway are potential targets for antibacterial agents.
Bacher
A
A
Lehrstuhl für Organische Chemie und Biochemie, Technische Universität München, D-85747 Garching, Germany.
Eberhardt
S
S
Eisenreich
W
W
Fischer
M
M
Herz
S
S
Illarionov
B
B
Kis
K
K
Richter
G
G
D001412:Bacillus subtilis / Q000201:enzymology* / Q000235:genetics; D005285:Fermentation; D006801:Humans; D007700:Kinetics; D012256:Riboflavin / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000737:chemistry; D012258:Riboflavin Synthase / Q000737:chemistry / Q000378:metabolism*
D012258:Riboflavin Synthase; D012256:Riboflavin