All Topics  
Flavin

 

 
   Email Print
   Bookmark   Link
 

 

Flavin
 
 
  Topics Flavin Topic Home

Flavin (from Latin flavus, "yellow") is the common name for a group of organic compounds based on pteridine
Pteridine

Pteridine is a chemical compound composed of fused pyrimidine and pyrazine rings. A pteridine is also a group of heterocyclic compounds containing a wide variety of substitutions on this structure....
, formed by the tricyclic heteronuclear organic ring isoalloxazine. The biochemical source is the vitamin riboflavin
Riboflavin

Riboflavin , also known as vitamin B2, is an easily absorbed micronutrient with a key role in maintaining health in humans and animals....
. The flavin moiety
Functional group

In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules....
 is often attached with an adenosine diphosphate
Adenosine diphosphate

Adenosine diphosphate, abbreviated ADP, is a nucleotide. It is an ester of pyrophosphoric acid with the nucleoside adenosine. ADP consists of the pyrophosphate Functional group, the pentose sugar ribose, and the nucleobase adenine....
 to form flavin adenine dinucleotide (FAD), and, in other circumstances, is found as flavin mononucleotide
Flavin mononucleotide

Flavin mononucleotide , or riboflavin-5'-phosphate, is a biomolecule produced from riboflavin by the enzyme riboflavin kinase and functions as prosthetic group of various oxidoreductases including NADH dehydrogenase....
 (or FMN), a phosphorylated form of riboflavin
Riboflavin

Riboflavin , also known as vitamin B2, is an easily absorbed micronutrient with a key role in maintaining health in humans and animals....
.






Discussion
Ask a question about 'Flavin'
Start a new discussion about 'Flavin'
Answer questions from other users
Full Discussion Forum



Encyclopedia


Flavin (from Latin flavus, "yellow") is the common name for a group of organic compounds based on pteridine
Pteridine

Pteridine is a chemical compound composed of fused pyrimidine and pyrazine rings. A pteridine is also a group of heterocyclic compounds containing a wide variety of substitutions on this structure....
, formed by the tricyclic heteronuclear organic ring isoalloxazine. The biochemical source is the vitamin riboflavin
Riboflavin

Riboflavin , also known as vitamin B2, is an easily absorbed micronutrient with a key role in maintaining health in humans and animals....
. The flavin moiety
Functional group

In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules....
 is often attached with an adenosine diphosphate
Adenosine diphosphate

Adenosine diphosphate, abbreviated ADP, is a nucleotide. It is an ester of pyrophosphoric acid with the nucleoside adenosine. ADP consists of the pyrophosphate Functional group, the pentose sugar ribose, and the nucleobase adenine....
 to form flavin adenine dinucleotide (FAD), and, in other circumstances, is found as flavin mononucleotide
Flavin mononucleotide

Flavin mononucleotide , or riboflavin-5'-phosphate, is a biomolecule produced from riboflavin by the enzyme riboflavin kinase and functions as prosthetic group of various oxidoreductases including NADH dehydrogenase....
 (or FMN), a phosphorylated form of riboflavin
Riboflavin

Riboflavin , also known as vitamin B2, is an easily absorbed micronutrient with a key role in maintaining health in humans and animals....
. It is in one or the other of these forms that flavin is present as a prosthetic group
Prosthetic group

A prosthetic group is a non-protein component of a conjugated protein that is required for the protein's biological activity. The prosthetic group may be organic compound or inorganic ....
 in flavoproteins.

The flavin group is capable of undergoing oxidation-reduction reactions, and can accept either one electron
Electron

The electron is a subatomic particle that carries a negative electric charge. It has elementary particle and is believed to be a point particle....
 in a two-step process or two electrons at once. Reduction is made with the addition of hydrogen
Hydrogen

Hydrogen is the chemical element with atomic number 1. It is represented by the chemical symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly combustion and explosive Diatomic molecule gas with the molecular formula H2....
 atoms to specific nitrogen
Nitrogen

Nitrogen is a chemical element that has the symbol N and atomic number 7 and atomic mass 14.00674?. Elemental nitrogen is a colorless, odorless, tasteless and mostly inert diatomic gas at standard conditions, constituting 78% by volume of Earth's atmosphere....
 atoms on the isoalloxazine ring system:

In aqueous solution
Aqueous solution

An aqueous solution is a solution in which the solvent is water. It is usually shown in chemical equations by appending to the relevant formula....
, flavins are yellow-coloured when oxidized, taking a red colour in the semi-reduced anionic state or blue in the neutral (semiquinone
Semiquinone

An Ubisemiquinone is a free radical resulting from the removal of one hydrogen atom with its electron during the process of dehydrogenation of a hydroquinone to quinone or alternatively the addition of a single H atom to a quinone....
) state, and colourless when totally reduced. The oxidized and reduced forms are in fast equilibrium
Chemical equilibrium

In a chemical process, chemical equilibrium is the state in which the Activity or concentrations of the reactants and products have no net change over time....
 with the semiquinone (radical
Radical

Radical may refer to:in science* In chemistry, a Radical is an atom, molecule, or ion which is likely to take part in chemical reactions.*The symbol v used to indicate the square root or nth root...
) form, shifted against the formation of the radical:

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.

Photoreduction

Both free and protein-bound flavins are photoreducible, that is, able to be reduced by light
Light

Light, or visible light, is electromagnetic radiation of a wavelength that is Visible spectrum to the human eye , or up to 380?750 nm. In the broader field of physics, light is sometimes used to refer to electromagnetic radiation of all wavelengths, whether visible or not....
, in a mechanism mediated by several organic compounds, such as some aminoacids, carboxylic acid
Carboxylic acid

Carboxylic acids are organic acids characterized by the presence of a carboxyl group, which has the Chemical formula -COH, usually written -COOH or -CO2H....
s and amine
Amine

Amines are organic compounds and functional groups that contain a base nitrogen atom with a lone pair. Amines are derivative s of ammonia, wherein one or more hydrogen atoms are replaced by organic substituents such as alkyl and aryl groups....
s.

FAD

Flavin adenine dinucleotide is a group bound to many enzymes including ferredoxin-NADP+ reductase
Ferredoxin-NADP+ reductase

In enzymology, a ferredoxin---NADP+ reductase is an enzyme that catalysis the chemical reactionThe 3 substrate of this enzyme are reduced ferredoxin, nicotinamide adenine dinucleotide phosphate, and hydrogen ion, whereas its two product are oxidized ferredoxin and nicotinamide adenine dinucleotide phosphate....
, monoamine oxidase
Monoamine oxidase

Monoamine oxidases are enzymes that catalysis the oxidation of monoamines. They are found bound to the outer membrane of mitochondria in most cell types in the body....
, D-amino acid oxidase
D-amino acid oxidase

D-amino acid oxidase is a peroxisomal enzyme containing FAD as cofactor spread from yeasts to human. It is not present in bacteria or in plants....
, glucose oxidase
Glucose oxidase

The glucose oxidase enzyme binds to beta-D-glucopyranose and aids in breaking the sugar down into its metabolites. GOx is a dimeric protein that catalysts the oxidation of beta-D-glucose into Glucono delta-lactone, which then hydrolysiss to gluconic acid....
, xanthine oxidase
Xanthine oxidase

The enzyme xanthine oxidase, or XO, catalyzes the oxidation of hypoxanthine to xanthine and can further catalyze the oxidation of xanthine to uric acid....
, and acyl CoA dehydrogenase
Acyl CoA dehydrogenase

Acyl-CoA dehydrogenases are a class of enzymes which function to catalyze the initial step in each cycle of fatty acid ? -oxidation in the mitochondria of cells....
.

FADH/FADH2

FADH and FADH2 are reduced
Redox

Redox describes all chemical reactions in which atoms have their oxidation number changed.This can be either a simple redox process such as the oxidation of carbon to yield carbon dioxide or the reduction of carbon by hydrogen to yield methane , or it can be a complex process such as the oxidation of sugar in the human body through a ser...
 forms of FAD. FADH2 is produced as a prosthetic group in succinate dehydrogenase, an enzyme involved in the citric acid cycle
Citric acid cycle

The citric acid cycle ? also known as the tricarboxylic acid cycle ; the Krebs cycle; or, more rarely, the Szent-Gy?rgyi-Krebs cycle) ? is a series of enzyme-catalysed chemical reactions of central importance in all living cell s that use oxygen as part of cellular respiration....
. In oxidative phosphorylation
Oxidative phosphorylation

Oxidative phosphorylation is a metabolic pathway that uses energy released by the redox of nutrients to produce adenosine triphosphate . Although the many forms of life on earth use a range of different nutrients, almost all carry out oxidative phosphorylation to produce ATP, the molecule that supplies energy to metabolism....
, two molecules of FADH2 typically yield 1.5 ATP
Adenosine triphosphate

This article is about the chemical used by cells as an energy carrier. For other uses, see ATP .Adenosine-5'-triphosphate is a multifunctional nucleotide, and plays an important role in cell biology as a coenzyme that is the "molecule unit of currency" of intracellular energy transfer....
 each, or three ATP combined.

FMN

Flavin mononucleotide
Flavin mononucleotide

Flavin mononucleotide , or riboflavin-5'-phosphate, is a biomolecule produced from riboflavin by the enzyme riboflavin kinase and functions as prosthetic group of various oxidoreductases including NADH dehydrogenase....
 is a prosthetic group
Prosthetic group

A prosthetic group is a non-protein component of a conjugated protein that is required for the protein's biological activity. The prosthetic group may be organic compound or inorganic ....
 found in, among other proteins, NADH dehydrogenase
NADH dehydrogenase

NADH dehydrogenase is an enzyme located in the inner mitochondria membrane that catalyzes the transfer of electrons from NADH to coenzyme Q ....
, E.coli nitroreductase
E. coli nitroreductase

E. coli nitroreductase is a flavoprotein found in the bacteria Escherichia coli. It catalyses the reduction of Nitro compound in a wide range of substrates, to produce the corresponding hydroxylamine....
 and old yellow enzyme.

Use as a dye

Flavin is the most important coloring matter obtained from quercitron
Quercitron

Quercitron is a yellow dye obtained from the bark of the Eastern Black Oak , a fine forest tree indigenous in North America. The name is a shortened form of quercicitron, from Latin quercus, oak, and citron, lemon, and was invented by Dr Edward Bancroft , who by act of parliament in 1785 was granted special privileges in regard to t...
 (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
Quercetin

Quercetin is a plant-derived flavonoid, specifically a flavonol, used as a nutritional supplement.The American Cancer Society says that quercetin "has been promoted as being effective against a wide variety of diseases, including cancer....
.

See also

  • Pteridine
    Pteridine

    Pteridine is a chemical compound composed of fused pyrimidine and pyrazine rings. A pteridine is also a group of heterocyclic compounds containing a wide variety of substitutions on this structure....
  • Pterin
    Pterin

    Pterin is a heterocycle compound composed of a pyrazine ring and a pyrimidine ring ; the pyrimidine ring has a carbonyl oxygen and an amino group....