Flavin group

flavinisoalloxazine ringflavinsflavineFADH 2 flavinatorflavoenzymeflavoenzymesisoalloxazine
Flavin (from Latin flavus, "yellow") is the common name for a group of organic compounds based on pteridine, formed by the tricyclic heterocycle isoalloxazine.wikipedia
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Flavin adenine dinucleotide

FADFADH 2 FADH2
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.
A flavoprotein is a protein that contains a flavin group, this may be in the form of FAD or flavin mononucleotide (FMN).

Cofactor (biochemistry)

cofactorcofactorscoenzyme
It is in one or the other of these forms that flavin is present as a prosthetic group in flavoproteins.
Cofactors can be divided into two major groups: organic Cofactors, such as flavin or heme, and inorganic cofactors, such as the metal ions Mg 2+, Cu +, Mn 2+, or iron-sulfur clusters.

Pteridine

Flavin (from Latin flavus, "yellow") is the common name for a group of organic compounds based on pteridine, formed by the tricyclic heterocycle isoalloxazine.
Pterins and flavins are classes of substituted pteridines that have diverse biological roles.

Ferredoxin—NADP(+) reductase

Ferredoxin-NADP + reductaseferredoxin-NADP+ reductaseEC 1.18.1.2
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.
It has a flavin cofactor, FAD.

Riboflavin

vitamin B 2 B 2 vitamin B2
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. The biochemical source is the vitamin riboflavin.
The name "riboflavin" (often abbreviated to Rbf or RBF) comes from "ribose" (the sugar whose reduced form, ribitol, forms part of its structure) and "flavin", the ring-moiety which imparts the yellow color to the oxidized molecule (from Latin flavus, "yellow").

Xanthine oxidase

xanthine oxidoreductaseoxidase
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.
The protein is large, having a molecular weight of 270 kDa, and has 2 flavin molecules (bound as FAD), 2 molybdenum atoms, and 8 iron atoms bound per enzymatic unit.

D-amino acid oxidase

D -amino acid oxidaseD-amino-acid oxidaseDAO
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.
Human DAAO has slightly different properties from other DAAO molecules, including a weaker ability to bind FAD and decreased rate of reaction for some molecules, such as flavin.

Oxidative phosphorylation

ATP generationmitochondrial oxidative phosphorylationoxidative
In oxidative phosphorylation, two molecules of FADH 2 typically yield 1.5 ATP each, or three ATP combined.
Within proteins, electrons are transferred between flavin cofactors, iron–sulfur clusters, and cytochromes.

Succinate dehydrogenase

Complex IISDHsuccinate - coenzyme Q reductase
FADH 2 is produced as a prosthetic group in succinate dehydrogenase, an enzyme involved in the citric acid cycle.
The function of SDHE has been described as a flavinator of succinate dehydrogenase.

Adenosine triphosphate

ATPadenosine triphosphate (ATP)adenosine 5'-triphosphate
In oxidative phosphorylation, two molecules of FADH 2 typically yield 1.5 ATP each, or three ATP combined.
Every "turn" of the citric acid cycle produces two molecules of carbon dioxide, one equivalent of ATP guanosine triphosphate (GTP) through substrate-level phosphorylation catalyzed by succinyl-CoA synthetase, as succinyl- CoA is converted to Succinate, three equivalents of NADH, and one equivalent of FADH 2.

Organic compound

syntheticorganicorganic compounds
Flavin (from Latin flavus, "yellow") is the common name for a group of organic compounds based on pteridine, formed by the tricyclic heterocycle isoalloxazine.

Heterocyclic compound

heterocyclicheterocycleheterocycles
Flavin (from Latin flavus, "yellow") is the common name for a group of organic compounds based on pteridine, formed by the tricyclic heterocycle isoalloxazine.

Functional group

groupfunctional groupsmoiety
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.

Adenosine diphosphate

ADPadenosine diphosphate (ADP)adenosine diphosphate sugars
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.

Flavin mononucleotide

FMNflavinsRiboflavin-5'-Phosphate
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.

Phosphorylation

phosphorylatedphosphorylatephosphorylates
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.

Flavoprotein

flavoproteinsflavoenzymeflavoprotein complexes
It is in one or the other of these forms that flavin is present as a prosthetic group in flavoproteins.

Electron

electronse − electron mass
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.

Hydrogen

HH 2 hydrogen gas
Reduction is made with the addition of hydrogen atoms to specific nitrogen atoms on the isoalloxazine ring system:

Nitrogen

NN 2 dinitrogen
Reduction is made with the addition of hydrogen atoms to specific nitrogen atoms on the isoalloxazine ring system:

Aqueous solution

aqueouswater solubilityaqueous solutions
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.

Semiquinone

Semidioneubisemiquinone
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.

Chemical equilibrium

equilibriumchemical equilibriaequilibria
The oxidized and reduced forms are in fast equilibrium with the semiquinone (radical) form, shifted against the formation of the radical:

Radical (chemistry)

free radicalradicalfree radicals
The oxidized and reduced forms are in fast equilibrium with the semiquinone (radical) form, shifted against the formation of the radical: