title: Biosynthesis of riboflavin. 6,7-Dimethyl-8-ribityllumazine 5'-phosphate is not a substrate for riboflavin synthase.
abstract: Phosphotransferase from carrot is shown to catalyze the phosphorylation of 6,7-dimethyl-8-ribityllumazine specifically at position 5' of the ribityl side chain. The lumazine 5'-phosphate is neither a substrate nor an inhibitor of riboflavin synthase from Bacillus subtilis and Escherichia coli. It follows that the obligatory product of riboflavin synthase is riboflavin and not FMN.
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology; D004926:Escherichia coli / Q000201:enzymology; D010770:Phosphotransferases / Q000378:metabolism; D011621:Pteridines / Q000378:metabolism; D012256:Riboflavin / Q000096:biosynthesis*; D012258:Riboflavin Synthase / Q000378:metabolism*; D012266:Ribose / Q000031:analogs & derivatives / Q000378:metabolism; D012267:Ribosemonophosphates / Q000378:metabolism; D013379:Substrate Specificity; D014166:Transferases / Q000378:metabolism*
chemical_list: D011621:Pteridines; D012267:Ribosemonophosphates; C001061:6,7-dimethyl-8-ribityllumazine; D012266:Ribose; D014166:Transferases; D012258:Riboflavin Synthase; D010770:Phosphotransferases; D012256:Riboflavin