IUBMB Enzyme Nomenclature


Accepted name: riboflavin kinase

Reaction: ATP + riboflavin = ADP + FMN

For diagram of reaction click here.

Other name(s): flavokinase; FK; RFK

Systematic name: ATP:riboflavin 5'-phosphotransferase

Comments: The cofactors FMN and FAD participate in numerous processes in all organisms, including mitochondrial electron transport, photosynthesis, fatty-acid oxidation, and metabolism of vitamin B6, vitamin B12 and folates [5]. While monofunctional riboflavin kinase is found in eukaryotes, some bacteria have a bifunctional enzyme that exhibits both this activity and that of EC, FMN adenylyltransferase [5]. A divalent metal cation is required for activity (with different species preferring Mg2+, Mn2+ or Zn2+). In Bacillus subtilis, ATP can be replaced by other phosphate donors but with decreasing enzyme activity in the order ATP > dATP > CTP > UTP [6].

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 9032-82-0


1. Chassy, B.M., Arsenis, C. and McCormick, D.B. The effect of the length of the side chain of flavins on reactivity with flavokinase. J. Biol. Chem. 240 (1965) 1338-1340. [PMID: 14284745]

2. Giri, K.V., Krishnaswamy, P.R. and Rao, N.A. Studies on plant flavokinase. Biochem. J. 70 (1958) 66-71. [PMID: 13584303]

3. Kearney, E.B. The interaction of yeast flavokinase with riboflavin analogues. J. Biol. Chem. 194 (1952) 747-754. [PMID: 14927668]

4. McCormick, D.B. and Butler, R.C. Substrate specificity of liver flavokinase. Biochim. Biophys. Acta 65 (1962) 326-332.

5. Sandoval, F.J. and Roje, S. An FMN hydrolase is fused to a riboflavin kinase homolog in plants. J. Biol. Chem. 280 (2005) 38337-38345. [PMID: 16183635]

6. Solovieva, I.M., Tarasov, K.V. and Perumov, D.A. Main physicochemical features of monofunctional flavokinase from Bacillus subtilis. Biochemistry (Mosc) 68 (2003) 177-181. [PMID: 12693963]

7. Solovieva, I.M., Kreneva, R.A., Leak, D.J. and Perumov, D.A. The ribR gene encodes a monofunctional riboflavin kinase which is involved in regulation of the Bacillus subtilis riboflavin operon. Microbiology 145 (1999) 67-73. [PMID: 10206712]

[EC created 1961, modified 2007]

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