Flavoprotein


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Related to Flavoprotein: flavin, dehydrogenase, cytochrome, ubiquinone

flavoprotein

[¦fla·vō¦prō‚tēn]
(biochemistry)
Any of a number of conjugated protein dehydrogenases containing flavin that play a role in biological oxidations in both plants and animals; a yellow enzyme.

Flavoprotein

 

(also flavin enzyme or yellow enzyme), any one of a group of complex enzymes, whose riboflavin derivatives—flavin adenine dinucleotide (FAD) or flavin mononucleotide (FMN)—serve as prosthetic groups (non-protein components). Flavoproteins were discovered in 1932 by O. Warburg.

The prosthetic group of many flavoproteins contains, in addition to flavin nucleotides, metals (Fe, Cu, Mo), sulfur compounds, and other compounds. The metals are complexly bound to the flavin nucleotides. When in an oxidized state, most flavoproteins are colored yellow and have characteristic absorption bands in the ranges 350–380 and 450–460 nanometers; in a reduced state, they are colorless. Flavoproteins are related to the oxidoreductase class and catalyze important oxidation-reduction reactions in living organisms with the direct participation of FAD and, more rarely, FMN. The specificity (selectivity) and effectiveness of the action of flavoproteins are determined by the nature of their protein components (apoenzymes), which have still not been adequately studied. Most flavoproteins are associated with cell membranes, forming strong complexes with lipids that are part of their composition.

The primary function of flavoproteins is the oxidation of reduced nicotinamide adenine dinucleotide in electron transfer chains (seeOXIDATIVE PHOSPHORYLATION). Flavoproteins are also capable of directly oxidizing various substrates and detaching from them hydrogen atoms, which are then transferred onto oxygen either immediately (for example, xanthine oxidase) or through the chain of transfer of electrons (for example, succinate dehydrogenase).

Flavoproteins are abundant in nature; they participate in the catabolism of major classes of organic compounds in the cells of animals, plants, and microorganisms.

REFERENCE

Lehninger, A. Biokhimiia. Moscow, 1976. (Translated from English.)

N. N. CHERNOV

References in periodicals archive ?
MADD may be caused by mutations in the electron transfer flavoprotein alpha subunit (ETFA), [4] electron transfer flavoprotein beta subunit (ETFB), or electron transfer flavoprotein dehydrogenase (ETFDH) genes.
B2 is needed to create the essential flavoprotein coenzymes for synthesis of L-methylfolate--the active form of folate--and for proper utilization of B6.
Thioredoxin reductase (TrxR) is a selenoenzyme and flavoprotein that cacalyzes the nicotinamide adenine dinucleotide phosphate (NADPH)-dependent reduction of thioredoxin (Trx) and other oxidized dithiols (Stadtman 2000).
The enzyme responsible for the first step is an acyl-CoA dehydrogenase, which transfers the electrons to an electron-transfer flavoprotein (ETF) and Coenzyme Q of the respiratory chain by using a second flavoprotein ETF: CoQ oxidorreductase, also named ETF dehydrogenase.
En la mayoria de los casos estas alteraciones se deben a la deficiencia de una de las tres proteinas necesarias a saber: subunidades alfa o beta de la flavoproteina de transferencia de electrones (ETF; OMIM #231680 y 130410, respectivamente; ETF: por la sigla en ingles de electron transfer flavoprotein.
In many migratory animals, the light-sensitive chemical reactions involving the flavoprotein cryptochrome (CRY) are thought to play an important role in the ability to sense the Earth's magnetic field.
A promising candidate radical pair comprises the reduced flavin cofactor (FAD) and an oxidized tryptophan residue in a cryptochrome flavoprotein (Solov'yov et al.
Other potential orbital antigens include thyroglobulin and cholinesterase epitopes, the flavoprotein subunit of the mitochondrial succinate dehydrogenase, a 55 kDa protein (G2s), calsequestrin and others (8-11).
electron transport: Successive passage of electrons from one cytochrome or flavoprotein to another by a series of oxidation-reduction reactions.
Oxidation is typically carried out by two families of genes, the flavoprotein monooxygenases (FMO) and the CYPs.
SDH catalyzes the oxidation of succinate to fumarate by reducing the flavine adenine dinucleotide (FAD) on its flavoprotein subunit.
Peroxisomes contain several ROS generating enzymes including glucose oxidase, amino acid oxidase, xanthine oxidase, glycollate and urate oxidase, as well as flavoprotein oxidases (12).