:"For the town in France, see Flavin, Aveyron".Flavin (from Latin "flavus", "yellow") is the common name for a group of organic compounds based on pteridine, formed by the tricyclic heteronuclear organic ring isoalloxazine. The biochemical source is the vitamin riboflavin. The flavin moiety is often attached with an adenosine diphosphate to form flavin adenine dinucleotide (FAD), and, in other circumstances, is found as flavin mononucleotide (or FMN), a phosphorylated form of riboflavin. It is in one or the other of these forms that flavin is present as a prosthetic group in flavoproteins.

The flavin group is capable of undergoing oxidation-reduction reactions, and can accept either one electron in a two-step process or two electrons at once. Reduction is made with the addition of hydrogen atoms to specific nitrogen atoms on the isoalloxazine ring system:

In aqueous solution, flavins are yellow-coloured when oxidized, taking a red colour in the semi-reduced anionic state or blue in the neutral (semiquinone) state, and colourless when totally reduced.cite journal |last= Michaelis|first= Leonor|authorlink= |coauthors=M. P. Schubert, C. V. Smythe |year= 1936|month= Dec|title= Potentiometric Study of the Flavins|journal= J. Biol. Chem.|volume= 116|number= 2|pages= 587–607|id= |url= http://www.jbc.org/cgi/reprint/116/2/587|accessdate= 2008-04-25] The oxidized and reduced forms are in fast equilibrium with the semiquinone (radical) form, shifted against the formation of the radical:cite journal |last= Massey|first= Vincent|authorlink= |coauthors=M. Stankovich, Peter Hemmerich |year= 1978|month= Jan|title= Light-Mediated Reduction of Flavoproteins with Flavins as Catalysts|journal= Biochemistry|volume= 17|number= 1|pages= 1–8|id= |url= http://pubs.acs.org/cgi-bin/archive.cgi/bichaw/1978/17/i01/pdf/bi00594a001.pdf|accessdate= 2008-04-25|doi= 10.1021/bi00594a001]

::Flox + FlredH2 ⇌ FlH

where Flox is the oxidized flavin, FlredH2 the reduced flavin (upon addition of two hydrogen atoms) and FlH the semiquinone form (addition of one hydrogen atom).

In the form of FADH2, it is one of the cofactors that can transfer electrons to the electron transfer chain.


Both free and protein-bound flavins are photoreducible, that is, able to be reduced by light, in a mechanism mediated by several organic compounds, such as some aminoacids, carboxylic acids and amines.


Flavin adenine dinucleotide is a group bound to many enzymes including ferredoxin-NADP+ reductase, monoamine oxidase, D-amino acid oxidase, glucose oxidase, xanthine oxidase, and acyl CoA dehydrogenase.


FADH and FADH2 are reduced forms of FAD. FADH2 is produced as a prosthetic group in succinate dehydrogenase, an enzyme involved in the citric acid cycle. In oxidative phosphorylation, two molecules of FADH2 typically yield 1.5 ATP each, or three ATP combined.


Flavin mononucleotide is a prosthetic group found in, among other proteins, NADH dehydrogenase, "E.coli" nitroreductase and old yellow enzyme.

Use as a dye

Flavin is the most important coloring matter obtained from quercitron (the bark of "Quercus velutina", also called dyer's oak). "Flavin" is the commercial name for quercitron. Two preparations are "yellow flavin" and "red flavin," which contains only quercetin. [http://en.wikipedia.org/wiki/New_International_Encyclopedia]

ee also



* Voet, D.; Voet, J.G. (2004). "Biochemistry" (3rd ed.). John Wiley & Sons. ISBN 0-471-39223-5

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  • FLAVIN (D.) — FLAVIN DAN (1933 1996) Artiste new yorkais, Dan Flavin est une des personnalités marquantes de l’art minimal, tant par la spécificité que par la cohérence de sa démarche. Depuis 1963, Dan Flavin réalise des constructions lumineuses, uniquement… …   Encyclopédie Universelle

  • Flavin — steht für: Flavine, Gruppe von natürlichen Farbstoffen Dan Flavin (1933–1996), US amerikanischer Künstler Martin Flavin (1883–1967), US amerikanischer Dramatiker und Schriftsteller Flavin (Aveyron), französische Ortschaft im Departement Aveyron …   Deutsch Wikipedia

  • Flavin — Saltar a navegación, búsqueda Flavin Flavinh País …   Wikipedia Español

  • Flavin — Fla vin, n. [L. flavus yellow.] (Chem.) A yellow, vegetable dyestuff, resembling quercitron. [1913 Webster] …   The Collaborative International Dictionary of English

  • Flavīn — Flavīn, C26H12N2O2, aus dem Producte der trockenen Destillation des benzoesauren Kalkes dargestellte organische Base, ist nach neueren Untersuchungen Carbanilid od. Anilin Harnstoff. Flavinschwefelsäure, Zersetzungsproduct der Indigschwefelsäure …   Pierer's Universal-Lexikon

  • Flavīn — Flavīn, s. Quercitron …   Meyers Großes Konversations-Lexikon

  • Flavin — Flavin, s. Farbstoffe, pflanzliche, Bd. 3, S. 635 …   Lexikon der gesamten Technik

  • Flavin — Flavīn, ein aus dem Querzitron durch Kochen seines Farbstoffs, des Querzitrins, mit verdünnten Säuren gewonnenes gelbes Pulver; dient zum Gelbfärben von Wolle …   Kleines Konversations-Lexikon

  • flavin — [flā′vin] n. [< L flavus, yellow (see FLAVONE) + IN1] 1. a complex heterocyclic ketone, C10H6N4O2 2. any of a group of yellow pigments, derived from this ketone and occurring in certain plant and animal products or prepared by synthesis;… …   English World dictionary

  • Flavin — Pour les articles homonymes, voir Dan Flavin et Martin Flavin. 44° 17′ 23″ N 2° 36′ 25″ E …   Wikipédia en Français

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