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Riboflavin synthase is an enzyme that catalyzes the final reaction of riboflavin biosynthesis. It catalyzes the transfer of a four-carbon unit from one molecule of 6,7-dimethyl-8-ribityllumazine onto another, resulting in the synthesis of riboflavin and 5-amino-6-ribitylamino-2,4(1 H ,3 H )-pyrimidinedione :
These two compounds are then the substrates for the penultimate step in the pathway, catalysed by the enzyme lumazine synthase in reaction EC 2.5.1.78. [12] [13] [14] In the final step of the biosynthesis, two molecules of 6,7-dimethyl-8-ribityllumazine are combined by the enzyme riboflavin synthase in a dismutation reaction. This generates one ...
2-Amino-5-formylamino-6-(5-phospho-D-ribosylamino)pyrimidin-4(3H)-one is a metabolite in the riboflavin biosynthesis pathway.It is formed from GTP by the enzyme GTP cyclohydrolase IIa which catalyzes the hydrolysis of the 8,9 bond in the guanine group and loss of the beta and gamma phosphate groups. [1]
Biosynthesis, i.e., chemical synthesis occurring in biological contexts, is a term most often referring to multi-step, enzyme-catalyzed processes where chemical substances absorbed as nutrients (or previously converted through biosynthesis) serve as enzyme substrates, with conversion by the living organism either into simpler or more complex ...
Guanosine triphosphate (GTP), the substrate of GTP cyclohydrolases. GTP cyclohydrolases are enzymes that catalyze imidazole ring opening of guanosine triphosphate (GTP). [1] This reaction is the committed step in the biosynthesis of multiple coenzymes (such as riboflavin and folate), tRNA bases, and the phytotoxin toxoflavin. [1]
The prokaryotic riboflavin biosynthesis protein is a bifunctional enzyme found in bacteria that catalyzes the phosphorylation of riboflavin into flavin mononucleotide (FMN) and the adenylylation of FMN into flavin adenine dinucleotide (FAD). It consists of a C-terminal riboflavin kinase and an N-terminal FMN-adenylyltransferase. This bacterial ...
R5P is produced in the pentose phosphate pathway in all organisms. [2] The pentose phosphate pathway (PPP) is a metabolic pathway that runs parallel to glycolysis. It is a crucial source for NADPH generation for reductive biosynthesis [3] (e.g. fatty acid synthesis) and pentose sugars. The pathway consists of two phases: an oxidative phase that ...
Riboflavin is generally ingested in the small intestine and then transported to cells via carrier proteins. [9] Riboflavin kinase (EC 2.7.1.26) adds a phosphate group to riboflavin to produce flavin mononucleotide, and then FAD synthetase attaches an adenine nucleotide; both steps require ATP. [9]