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Flavin mononucleotide (FMN), or riboflavin-5′-phosphate, is a biomolecule produced from riboflavin (vitamin B 2) 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]
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:
The flavin-containing monooxygenase (FMO) protein family specializes in the oxidation of xeno-substrates in order to facilitate the excretion of these compounds from living organisms. [1] These enzymes can oxidize a wide array of heteroatoms, particularly soft nucleophiles, such as amines, sulfides, and phosphites.
90 flavoproteins are encoded in the human genome; about 84% require FAD and around 16% require FMN, whereas 5 proteins require both. [4] Flavoproteins are mainly located in the mitochondria . [ 4 ] Of all flavoproteins, 90% perform redox reactions and the other 10% are transferases , lyases , isomerases , ligases .
Riboflavin is reversibly converted to FMN and then FAD. From riboflavin to FMN is the function of zinc-requiring riboflavin kinase; the reverse is accomplished by a phosphatase. From FMN to FAD is the function of magnesium-requiring FAD synthase; the reverse is accomplished by a pyrophosphatase. FAD appears to be an inhibitory end-product that ...
Two types of P450 systems are found in eukaryotes. The P450 systems that are located in the endoplasmic reticulum are dependent on a cytochrome P-450 reductase (CPR) that contains both an FAD and an FMN. The two electrons on reduced FAD (FADH 2) are transferred one at a time to FMN and then a single electron is passed from FMN to the heme of ...
An electron transport chain (ETC [1]) is a series of protein complexes and other molecules which transfer electrons from electron donors to electron acceptors via redox reactions (both reduction and oxidation occurring simultaneously) and couples this electron transfer with the transfer of protons (H + ions) across a membrane.
In enzymology, an FMN reductase (EC 1.5.1.29) is an enzyme that catalyzes the chemical reaction FMNH 2 + NAD(P)+ ⇌ {\displaystyle \rightleftharpoons } FMN + NAD(P)H + H + The 3 substrates of this enzyme are FMNH2 , NAD + , and NADP + , whereas its 4 products are FMN , NADH , NADPH , and H + .