Flavin mononucleotide explained

Flavin mononucleotide (FMN), or riboflavin-5′-phosphate, is a biomolecule produced from riboflavin (vitamin B₂) by the enzyme riboflavin kinase and functions as the prosthetic group of various oxidoreductases, including NADH dehydrogenase, as well as a cofactor in biological blue-light photo receptors.^[1] During the catalytic cycle, a reversible interconversion of the oxidized (FMN), semiquinone (FMNH^•), and reduced (FMNH₂) forms occurs in the various oxidoreductases. FMN is a stronger oxidizing agent than NAD and is particularly useful because it can take part in both one- and two-electron transfers. In its role as blue-light photo receptor, (oxidized) FMN stands out from the 'conventional' photo receptors as the signaling state and not an E/Z isomerization.

It is the principal form in which riboflavin is found in cells and tissues. It requires more energy to produce, but is more soluble than riboflavin. In cells, FMN occurs freely circulating but also in several covalently bound forms.^[2] Covalently or non-covalently bound FMN is a cofactor of many enzymes playing an important pathophysiological role in cellular metabolism. For example dissociation of flavin mononucleotide from mitochondrial complex I has been shown to occur during ischemia/reperfusion brain injury during stroke.^{[3] [4]}

Food additive

Flavin mononucleotide is also used as an orange-red food colour additive, designated in Europe as E number E101a.^[5]

E106, a very closely related food dye, is riboflavin-5′-phosphate sodium salt, which consists mainly of the monosodium salt of the 5′-monophosphate ester of riboflavin. It is rapidly turned to free riboflavin after ingestion. It is found in many foods for babies and young children as well as jams, milk products, and sweets and sugar products.^[6]

See also

• Flavin adenine dinucleotide

External links

• FMN in the EBI Macromolecular Structure Database

Notes and References

1. Studies on the Binding and Function of Flavin Phosphates with Flavin Mononucleotide-dependent Enzymes. John C. M. . Tsibris. Donald B. . McCormick . Lemuel D.. Wright. Journal of Biological Chemistry. 1966 . 241 . 5 . 1138–43 . 10.1016/S0021-9258(18)96813-4 . 4379862 . free .
2. 10.1002/pro.5560070102 . free . Covalent attachment of flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) to enzymes: The current state of affairs . 1998 . Mewies M, McIntire WS, Scrutton NS . Protein Science . 7 . 1 . 7–20 . 9514256 . 2143808 .
3. Kahl . A . Stepanova . A . Konrad . C . Anderson . C . Manfredi . G . Zhou . P . Iadecola . C . Galkin . A . Critical Role of Flavin and Glutathione in Complex I-Mediated Bioenergetic Failure in Brain Ischemia/Reperfusion Injury. . Stroke . 2018 . 49 . 5 . 1223–1231 . 10.1161/STROKEAHA.117.019687 . 29643256. 5916474 .
4. Galkin . A . Brain Ischemia/Reperfusion Injury and Mitochondrial Complex I Damage. . Biochemistry. Biokhimiia . 2019 . 84 . 11 . 1411–1423 . 10.1134/S0006297919110154 . 31760927. 207990089 .
5. "Current EU approved additives and their E Numbers", Food Standards Agency website, retrieved 15 Dec 2011
6. 10.2903/j.efsa.2017.4919 . Dietary Reference Values for riboflavin . 2017 . Turck . Dominique . Bresson . Jean‐Louis . Burlingame . Barbara . Dean . Tara . Fairweather‐Tait . Susan . Heinonen . Marina . Hirsch‐Ernst . Karen Ildico . Mangelsdorf . Inge . McArdle . Harry J. . Naska . Androniki . Nowicka . Grażyna . Pentieva . Kristina . Sanz . Yolanda . Siani . Alfonso . Sjödin . Anders . Stern . Martin . Tomé . Daniel . Van Loveren . Henk . Vinceti . Marco . Willatts . Peter . Lamberg‐Allardt . Christel . Przyrembel . Hildegard . Tetens . Inge . Dumas . Céline . Fabiani . Lucia . Forss . Annette Cecilia . Ioannidou . Sofia . Neuhäuser‐Berthold . Monika . Neuhäuser-Berthold . 3 . M. . EFSA Journal . 15 . 8 . e04919 . 32625611 . 7010026 .