IUBMB Enzyme Nomenclature


Accepted name: nicotinate-nucleotide—dimethylbenzimidazole phosphoribosyltransferase

Reaction: β-nicotinate D-ribonucleotide + 5,6-dimethylbenzimidazole = nicotinate + α-ribazole 5'-phosphate

For diagram click here.

Glossary: α-ribazole 5′-phosphate = N1-(5-phospho-α-D-ribosyl)-5,6-dimethylbenzimidazole

Other name(s): nicotinate mononucleotide-dimethylbenzimidazole phosphoribosyltransferase; nicotinate ribonucleotide:benzimidazole (adenine) phosphoribosyltransferase; nicotinate-nucleotide:dimethylbenzimidazole phospho-D-ribosyltransferase; CobT; nicotinate mononucleotide (NaMN):5,6-dimethylbenzimidazole phosphoribosyltransferase

Systematic name: nicotinate-nucleotide:5,6-dimethylbenzimidazole phospho-D-ribosyltransferase

Comments: Also acts on benzimidazole, and the clostridial enzyme acts on adenine to form 7-α-D-ribosyladenine 5′-phosphate. The product of the reaction, α-ribazole 5′-phosphate, forms part of the corrin-biosynthesis pathway and is a substrate for EC, adenosylcobinamide-GDP ribazoletransferase [4]. It can also be dephosphorylated to form α-ribazole by the action of EC, α-ribazole phosphatase.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 37277-76-2


1. Friedmann, H.C. Partial purification and properties of a single displacement trans-N-glycosidase. J. Biol. Chem. 240 (1965) 413-418. [PMID: 14253445]

2. Friedmann, H.C. and Fyfe, J.A. Pseudovitamin B12 biosynthesis. Enzymatic formation of a new adenylic acid, 7-α-D-ribofuranosyladenine 5'-phosphate. J. Biol. Chem. 244 (1969) 1667-1671. [PMID: 5780835]

3. Fyfe, J.A. and Friedmann, H.C. Vitamin B12 biosynthesis. Enzyme studies on the formation of the α-glycosidic nucleotide precursor. J. Biol. Chem. 244 (1969) 1659-1666. [PMID: 4238408]

4. Cameron, B., Blanche, F., Rouyez, M.C., Bisch, D., Famechon, A., Couder, M., Cauchois, L., Thibaut, D., Debussche, L. and Crouzet, J. Genetic analysis, nucleotide sequence, and products of two Pseudomonas denitrificans cob genes encoding nicotinate-nucleotide: dimethylbenzimidazole phosphoribosyltransferase and cobalamin (5'-phosphate) synthase. J. Bacteriol. 173 (1991) 6066-6073. [PMID: 1917841]

5. Cheong, C.G., Escalante-Semerena, J.C. and Rayment, I. Structural investigation of the biosynthesis of alternative lower ligands for cobamides by nicotinate mononucleotide: 5,6-dimethylbenzimidazole phosphoribosyltransferase from Salmonella enterica. J. Biol. Chem. 276 (2001) 37612-37620. [PMID: 11441022]

6. Cheong, C.G., Escalante-Semerena, J.C. and Rayment, I. Capture of a labile substrate by expulsion of water molecules from the active site of nicotinate mononucleotide:5,6-dimethylbenzimidazole phosphoribosyltransferase (CobT) from Salmonella enterica. J. Biol. Chem. 277 (2002) 41120-41127. [PMID: 12101181]

[EC created 1972]

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