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Riboflavin is converted into catalytically active cofactors (FAD and FMN) by the actions of riboflavin kinase (EC 2.7.1.26), which converts it into FMN, and FAD synthetase (EC 2.7.7.2), which adenylates FMN to FAD. Eukaryotes usually have two separate enzymes, while most prokaryotes have a single bifunctional protein that can carry out both ...
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 biochemical source of flavin is the yellow B 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.
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 ...
In biochemistry, flavin adenine dinucleotide (FAD) is a redox-active coenzyme associated with various proteins, which is involved with several enzymatic reactions in metabolism. A flavoprotein is a protein that contains a flavin group , which may be in the form of FAD or flavin mononucleotide (FMN).
Flavoproteins have either FMN (flavin mononucleotide) or FAD (flavin adenine dinucleotide) as a prosthetic group or as a cofactor. The flavin is generally tightly bound (as in adrenodoxin reductase, wherein the FAD is buried deeply). [1] About 5-10% of flavoproteins have a covalently linked FAD. [2]
The prokaryotic riboflavin biosynthesis protein is a bifunctional enzyme found in bacteria that catalyzes the phosphorylation of riboflavin into flavin mononucleotide (FMN) and the adenylylation of FMN into flavin adenine dinucleotide (FAD). It consists of a C-terminal riboflavin kinase and an N-terminal FMN-adenylyltransferase. This bacterial ...
In enzymology, a FMN adenylyltransferase (EC 2.7.7.2) is an enzyme that catalyzes the chemical reaction ATP + FMN ⇌ {\displaystyle \rightleftharpoons } diphosphate + FAD Thus, the two substrates of this enzyme are ATP and FMN , whereas its two products are diphosphate and FAD .