An enzyme that utilizes NADH or NADPH to reduce FLAVINS. It is involved in a number of biological processes that require reduced flavin for their functions such as bacterial bioluminescence. Formerly listed as EC 1.6.8.1 and EC 1.5.1.29.
Organic esters or salts of sulfonic acid derivatives containing an aliphatic hydrocarbon radical.
A coenzyme for a number of oxidative enzymes including NADH DEHYDROGENASE. It is the principal form in which RIBOFLAVIN is found in cells and tissues.
Oxidoreductases that are specific for the reduction of NITRATES.
Enzymes that catalyze the reversible reduction of alpha-carboxyl group of 3-hydroxy-3-methylglutaryl-coenzyme A to yield MEVALONIC ACID.
A flavoprotein that catalyzes the reduction of heme-thiolate-dependent monooxygenases and is part of the microsomal hydroxylating system. EC 1.6.2.4.
Ribonucleotide Reductases are enzymes that catalyze the conversion of ribonucleotides to deoxyribonucleotides, which is a crucial step in DNA synthesis and repair, utilizing a radical mechanism for this conversion.
A FLAVOPROTEIN oxidoreductase that occurs both as a soluble enzyme and a membrane-bound enzyme due to ALTERNATIVE SPLICING of a single mRNA. The soluble form is present mainly in ERYTHROCYTES and is involved in the reduction of METHEMOGLOBIN. The membrane-bound form of the enzyme is found primarily in the ENDOPLASMIC RETICULUM and outer mitochondrial membrane, where it participates in the desaturation of FATTY ACIDS; CHOLESTEROL biosynthesis and drug metabolism. A deficiency in the enzyme can result in METHEMOGLOBINEMIA.
A group of enzymes that oxidize diverse nitrogenous substances to yield nitrite. (Enzyme Nomenclature, 1992) EC 1.
The class of all enzymes catalyzing oxidoreduction reactions. The substrate that is oxidized is regarded as a hydrogen donor. The systematic name is based on donor:acceptor oxidoreductase. The recommended name will be dehydrogenase, wherever this is possible; as an alternative, reductase can be used. Oxidase is only used in cases where O2 is the acceptor. (Enzyme Nomenclature, 1992, p9)
Catalyzes the oxidation of GLUTATHIONE to GLUTATHIONE DISULFIDE in the presence of NADP+. Deficiency in the enzyme is associated with HEMOLYTIC ANEMIA. Formerly listed as EC 1.6.4.2.
An enzyme that catalyzes the oxidation and reduction of FERREDOXIN or ADRENODOXIN in the presence of NADP. EC 1.18.1.2 was formerly listed as EC 1.6.7.1 and EC 1.6.99.4.
A FLAVOPROTEIN enzyme that catalyzes the oxidation of THIOREDOXINS to thioredoxin disulfide in the presence of NADP+. It was formerly listed as EC 1.6.4.5
Cytochrome reductases are enzymes that catalyze the transfer of electrons from donor molecules to cytochromes in electron transport chains, playing a crucial role in cellular respiration and energy production within cells.
A condensation product of riboflavin and adenosine diphosphate. The coenzyme of various aerobic dehydrogenases, e.g., D-amino acid oxidase and L-amino acid oxidase. (Lehninger, Principles of Biochemistry, 1982, p972)
Derivatives of the dimethylisoalloxazine (7,8-dimethylbenzo[g]pteridine-2,4(3H,10H)-dione) skeleton. Flavin derivatives serve an electron transfer function as ENZYME COFACTORS in FLAVOPROTEINS.
A group of oxidoreductases that act on NADH or NADPH. In general, enzymes using NADH or NADPH to reduce a substrate are classified according to the reverse reaction, in which NAD+ or NADP+ is formally regarded as an acceptor. This subclass includes only those enzymes in which some other redox carrier is the acceptor. (Enzyme Nomenclature, 1992, p100) EC 1.6.

Structural motif of phosphate-binding site common to various protein superfamilies: all-against-all structural comparison of protein-mononucleotide complexes. (1/253)

In order to search for a common structural motif in the phosphate-binding sites of protein-mononucleotide complexes, we investigated the structural variety of phosphate-binding schemes by an all-against-all comparison of 491 binding sites found in the Protein Data Bank. We found four frequently occurring structural motifs composed of protein atoms interacting with phosphate groups, each of which appears in different protein superfamilies with different folds. The most frequently occurring motif, which we call the structural P-loop, is shared by 13 superfamilies and is characterized by a four-residue fragment, GXXX, interacting with a phosphate group through the backbone atoms. Various sequence motifs, including Walker's A motif or the P-loop, turn out to be a structural P-loop found in a few specific superfamilies. The other three motifs are found in pairs of superfamilies: protein kinase and glutathione synthetase ATPase domain like, actin-like ATPase domain and nucleotidyltransferase, and FMN-linked oxidoreductase and PRTase.  (+info)

Iron reductase for magnetite synthesis in the magnetotactic bacterium Magnetospirillum magnetotacticum. (2/253)

Ferric iron reductase was purified from magnetotactic bacterium Magnetospirillum (formerly Aquaspirillum) magnetotacticum (ATCC 31632) to an electrophoretically homogeneous state. The enzyme was loosely bound on the cytoplasmic face of the cytoplasmic membrane and was found more frequently in magnetic cells than in nonmagnetic cells. The molecular mass of the purified enzyme was calculated upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis to be about 36 kDa, almost the same as that calibrated by gel filtration analysis. The enzyme required NADH and flavin mononucleotide (FMN) as optimal electron donor and cofactor, respectively, and the activity was strongly inhibited by Zn2+ acting as a partial mixed-type inhibitor. The Km values for NADH and FMN were 4.3 and 0. 035 microM, respectively, and the Ki values for Zn2+ were 19.2 and 23.9 microM for NADH and FMN, respectively. When the bacterium was grown in the presence of ZnSO4, the magnetosome number in the cells and the ferric iron reductase activity declined in parallel with an increase in the ZnSO4 concentration of the medium, suggesting that the ferric iron reductase purified in the present study may participate in magnetite synthesis.  (+info)

Genetic and physiologic characterization of ferric/cupric reductase constitutive mutants of Cryptococcus neoformans. (3/253)

Cryptococcus neoformans is a pathogenic yeast that causes meningitis in immunocompromised patients. Because iron acquisition is critical for growth of a pathogen in a host, we studied the regulation of the ferric reductase and ferrous uptake system of this organism. We isolated 18 mutants, representing four independent loci, with dysregulated ferric reductase. The mutant strains had >10-fold higher than wild-type WT reductase activity in the presence of iron. Two of the strains also had >7-fold higher than WT iron uptake in the presence of iron but were not markedly iron sensitive. Both were sensitive to the oxidative stresses associated with superoxide and hydrogen peroxide. One strain exhibited only 23% of the WT level of iron uptake in the absence of iron and grew poorly without iron supplementation of the medium, phenotypes consistent with an iron transport deficiency; it was sensitive to superoxide but not to hydrogen peroxide. The fourth strain had high reductase activity but normal iron uptake; it was not very sensitive to oxidative stress. We also demonstrated that the ferric reductase was regulated by copper and could act as a cupric reductase. Sensitivity to oxidants may be related to iron acquisition by a variety of mechanisms and may model the interaction of the yeast with the immune system.  (+info)

Crosstalk between the Ras2p-controlled mitogen-activated protein kinase and cAMP pathways during invasive growth of Saccharomyces cerevisiae. (4/253)

The two highly conserved RAS genes of the budding yeast Saccharomyces cerevisiae are redundant for viability. Here we show that haploid invasive growth development depends on RAS2 but not RAS1. Ras1p is not sufficiently expressed to induce invasive growth. Ras2p activates invasive growth using either of two downstream signaling pathways, the filamentation MAPK (Cdc42p/Ste20p/MAPK) cascade or the cAMP-dependent protein kinase (Cyr1p/cAMP/PKA) pathway. This signal branch point can be uncoupled in cells expressing Ras2p mutant proteins that carry amino acid substitutions in the adenylyl cyclase interaction domain and therefore activate invasive growth solely dependent on the MAPK cascade. Both Ras2p-controlled signaling pathways stimulate expression of the filamentation response element-driven reporter gene depending on the transcription factors Ste12p and Tec1p, indicating a crosstalk between the MAPK and the cAMP signaling pathways in haploid cells during invasive growth.  (+info)

The NAD(P)H:flavin oxidoreductase from Escherichia coli. Evidence for a new mode of binding for reduced pyridine nucleotides. (5/253)

The NAD(P)H:flavin oxidoreductase from Escherichia coli, named Fre, is a monomer of 26.2 kDa that catalyzes the reduction of free flavins using NADPH or NADH as electron donor. The enzyme does not contain any prosthetic group but accommodates both the reduced pyridine nucleotide and the flavin in a ternary complex prior to oxidoreduction. The specificity of the flavin reductase for the pyridine nucleotide was studied by steady-state kinetics using a variety of NADP analogs. Both the nicotinamide ring and the adenosine part of the substrate molecule have been found to be important for binding to the polypeptide chain. However, in the case of NADPH, the 2'-phosphate group destabilized almost completely the interaction with the adenosine moiety. Moreover, NADPH and NMNH are very good substrates for the flavin reductase, and we have shown that both these molecules bind to the enzyme almost exclusively by the nicotinamide ring. This provides evidence that the flavin reductase exhibits a unique mode for recognition of the reduced pyridine nucleotide. In addition, we have shown that the flavin reductase selectively transfers the pro-R hydrogen from the C-4 position of the nicotinamide ring and is therefore classified as an A-side-specific enzyme.  (+info)

Metronidazole resistance in the protozoan parasite Entamoeba histolytica is associated with increased expression of iron-containing superoxide dismutase and peroxiredoxin and decreased expression of ferredoxin 1 and flavin reductase. (6/253)

To obtain insight into the mechanism of metronidazole resistance in the protozoan parasite Entamoeba histolytica, amoeba trophozoites were selected in vitro by stepwise exposures to increasing amounts of metronidazole, starting with sublethal doses of 4 microM. Subsequently, amoebae made resistant were able to continuously multiply in the presence of a 40 microM concentration of the drug. In contrast to mechanisms of metronidazole resistance in other protozoan parasites, resistant amoebae did not substantially down-regulate pyruvate:ferredoxin oxidoreductase or up-regulate P-glycoproteins, but exhibited increased expression of iron-containing superoxide dismutase (Fe-SOD) and peroxiredoxin and decreased expression of flavin reductase and ferredoxin 1. Episomal transfection and overexpression of the various antioxidant enzymes revealed significant reduction in susceptibility to metronidazole only in those cells overexpressing Fe-SOD. Reduction was highest in transfected cells simultaneously overexpressing Fe-SOD and peroxiredoxin. Although induced overexpression of Fe-SOD did not confer metronidazole resistance to the extent found in drug-selected cells, transfected cells quickly adapted to constant exposures of otherwise lethal metronidazole concentrations. Moreover, metronidazole selection of transfected amoebae favored retention of the Fe-SOD-containing plasmid. These results strongly suggest that peroxiredoxin and, in particular, Fe-SOD together with ferredoxin 1 are important components involved in the mechanism of metronidazole resistance in E. histolytica.  (+info)

Characterization of a two-component alkanesulfonate monooxygenase from Escherichia coli. (7/253)

The Escherichia coli ssuEADCB gene cluster is required for the utilization of alkanesulfonates as sulfur sources, and is expressed under conditions of sulfate or cysteine starvation. The SsuD and SsuE proteins were overexpressed and characterized. SsuE was purified to homogeneity as an N-terminal histidine-tagged fusion protein. Native SsuE was a homodimeric enzyme of M(r) 58,400, which catalyzed an NAD(P)H-dependent reduction of FMN, but it was also able to reduce FAD or riboflavin. The SsuD protein was purified to >98% purity using cation exchange, anion exchange, and hydrophobic interaction chromatography. The pure enzyme catalyzed the conversion of pentanesulfonic acid to sulfite and pentaldehyde and was able to desulfonate a wide range of sulfonated substrates including C-2 to C-10 unsubstituted linear alkanesulfonates, substituted ethanesulfonic acids and sulfonated buffers. SsuD catalysis was absolutely dependent on FMNH(2) and oxygen, and was maximal for SsuE/SsuD molar ratios of 2.1 to 4.2 in 10 mM Tris-HCl, pH 9.1. Native SsuD was a homotetrameric enzyme of M(r) 181,000. These results demonstrate that SsuD is a broad range FMNH(2)-dependent monooxygenase catalyzing the oxygenolytic conversion of alkanesulfonates to sulfite and the corresponding aldehydes. SsuE is the FMN reducing enzyme providing SsuD with FMNH(2).  (+info)

Unusual folded conformation of nicotinamide adenine dinucleotide bound to flavin reductase P. (8/253)

The 2.1 A resolution crystal structure of flavin reductase P with the inhibitor nicotinamide adenine dinucleotide (NAD) bound in the active site has been determined. NAD adopts a novel, folded conformation in which the nicotinamide and adenine rings stack in parallel with an inter-ring distance of 3.6 A. The pyrophosphate binds next to the flavin cofactor isoalloxazine, while the stacked nicotinamide/adenine moiety faces away from the flavin. The observed NAD conformation is quite different from the extended conformations observed in other enzyme/NAD(P) structures; however, it resembles the conformation proposed for NAD in solution. The flavin reductase P/NAD structure provides new information about the conformational diversity of NAD, which is important for understanding catalysis. This structure offers the first crystallographic evidence of a folded NAD with ring stacking, and it is the first enzyme structure containing an FMN cofactor interacting with NAD(P). Analysis of the structure suggests a possible dynamic mechanism underlying NADPH substrate specificity and product release that involves unfolding and folding of NADP(H).  (+info)

Flavin Mononucleotide (FMN) Reductase is an enzyme that catalyzes the reduction of FMN to FMNH2 using NADH or NADPH as an electron donor. This enzyme plays a crucial role in the electron transport chain and is involved in various redox reactions within the cell. It is found in many organisms, including bacteria, fungi, plants, and animals. In humans, FMN Reductase is encoded by the RIBFLR gene and is primarily located in the mitochondria. Defects in this enzyme can lead to various metabolic disorders.

Alkanesulfonates are organic compounds that consist of a hydrocarbon chain, typically consisting of alkane molecules, which is bonded to a sulfonate group. The sulfonate group (-SO3-) consists of a sulfur atom bonded to three oxygen atoms, with one of the oxygen atoms carrying a negative charge.

Alkanesulfonates are commonly used as detergents and surfactants due to their ability to reduce surface tension and improve the wetting, emulsifying, and dispersing properties of liquids. They are also used in various industrial applications, such as in the production of paper, textiles, and leather.

In medical terms, alkanesulfonates may be used as topical antimicrobial agents or as ingredients in personal care products. However, some alkanesulfonates have been found to have potential health and environmental hazards, such as irritation of the skin and eyes, respiratory effects, and potential toxicity to aquatic life. Therefore, their use is subject to regulatory oversight and safety assessments.

Flavin Mononucleotide (FMN) is a coenzyme that plays a crucial role in biological oxidation-reduction reactions. It is derived from the vitamin riboflavin (also known as vitamin B2) and is composed of a flavin molecule bonded to a nucleotide. FMN functions as an electron carrier, accepting and donating electrons in various metabolic pathways, including the citric acid cycle and the electron transport chain, which are essential for energy production in cells. It also participates in the detoxification of harmful substances and contributes to the maintenance of cellular redox homeostasis. FMN can exist in two forms: the oxidized form (FMN) and the reduced form (FMNH2), depending on its involvement in redox reactions.

Nitrate reductases are a group of enzymes that catalyze the reduction of nitrate (NO3-) to nitrite (NO2-). This process is an essential part of the nitrogen cycle, where nitrate serves as a terminal electron acceptor in anaerobic respiration for many bacteria and archaea. In plants, this enzyme plays a crucial role in nitrogen assimilation by reducing nitrate to ammonium (NH4+), which can then be incorporated into organic compounds. Nitrate reductases require various cofactors, such as molybdenum, heme, and/or FAD, for their activity. There are three main types of nitrate reductases: membrane-bound (which use menaquinol as an electron donor), cytoplasmic (which use NADH or NADPH as an electron donor), and assimilatory (which also use NADH or NADPH as an electron donor).

Hydroxymethylglutaryl CoA (HMG-CoA) reductase is an enzyme that plays a crucial role in the synthesis of cholesterol in the body. It is found in the endoplasmic reticulum of cells and catalyzes the conversion of HMG-CoA to mevalonic acid, which is a key rate-limiting step in the cholesterol biosynthetic pathway.

The reaction catalyzed by HMG-CoA reductase is as follows:

HMG-CoA + 2 NADPH + 2 H+ → mevalonic acid + CoA + 2 NADP+

This enzyme is the target of statin drugs, which are commonly prescribed to lower cholesterol levels in the treatment of cardiovascular diseases. Statins work by inhibiting HMG-CoA reductase, thereby reducing the production of cholesterol in the body.

NADPH-ferrihemoprotein reductase, also known as diaphorase or NO synthase reductase, is an enzyme that catalyzes the reduction of ferrihemoproteins using NADPH as a reducing cofactor. This reaction plays a crucial role in various biological processes such as the detoxification of certain compounds and the regulation of cellular signaling pathways.

The systematic name for this enzyme is NADPH:ferrihemoprotein oxidoreductase, and it belongs to the family of oxidoreductases that use NADH or NADPH as electron donors. The reaction catalyzed by this enzyme can be represented as follows:

NADPH + H+ + ferrihemoprotein ↔ NADP+ + ferrohemoprotein

In this reaction, the ferric (FeIII) form of hemoproteins is reduced to its ferrous (FeII) form by accepting electrons from NADPH. This enzyme is widely distributed in various tissues and organisms, including bacteria, fungi, plants, and animals. It has been identified as a component of several multi-enzyme complexes involved in different metabolic pathways, such as nitric oxide synthase (NOS) and cytochrome P450 reductase.

In summary, NADPH-ferrihemoprotein reductase is an essential enzyme that catalyzes the reduction of ferrihemoproteins using NADPH as a reducing agent, playing a critical role in various biological processes and metabolic pathways.

Ribonucleotide Reductases (RNRs) are enzymes that play a crucial role in DNA synthesis and repair. They catalyze the conversion of ribonucleotides to deoxyribonucleotides, which are the building blocks of DNA. This process involves the reduction of the 2'-hydroxyl group of the ribose sugar to a hydrogen, resulting in the formation of deoxyribose.

RNRs are highly regulated and exist in various forms across different species. They are divided into three classes (I, II, and III) based on their structure, mechanism, and cofactor requirements. Class I RNRs are further divided into two subclasses (Ia and Ib), which differ in their active site architecture and regulation.

Class Ia RNRs, found in eukaryotes and some bacteria, contain a stable tyrosyl radical that acts as the catalytic center for hydrogen abstraction. Class Ib RNRs, found in many bacteria, use a pair of iron centers to perform the same function. Class II RNRs are present in some bacteria and archaea and utilize adenosine triphosphate (ATP) as a cofactor for reduction. Class III RNRs, found in anaerobic bacteria and archaea, use a unique mechanism involving a radical S-adenosylmethionine (SAM) cofactor to facilitate the reduction reaction.

RNRs are essential for DNA replication and repair, and their dysregulation has been linked to various diseases, including cancer and neurodegenerative disorders. Therefore, understanding the structure, function, and regulation of RNRs is of great interest in biochemistry, molecular biology, and medicine.

Nitrite reductases are a group of enzymes that catalyze the reduction of nitrite (NO2-) to nitric oxide (NO). This reaction is an important part of the nitrogen cycle, particularly in denitrification and dissimilatory nitrate reduction to ammonium (DNRA) processes. Nitrite reductases can be classified into two main types based on their metal co-factors: copper-containing nitrite reductases (CuNiRs) and cytochrome cd1 nitrite reductases. CuNiRs are typically found in bacteria and fungi, while cytochrome cd1 nitrite reductases are primarily found in bacteria. These enzymes play a crucial role in the global nitrogen cycle and have potential implications for environmental and medical research.

Oxidoreductases are a class of enzymes that catalyze oxidation-reduction reactions, which involve the transfer of electrons from one molecule (the reductant) to another (the oxidant). These enzymes play a crucial role in various biological processes, including energy production, metabolism, and detoxification.

The oxidoreductase-catalyzed reaction typically involves the donation of electrons from a reducing agent (donor) to an oxidizing agent (acceptor), often through the transfer of hydrogen atoms or hydride ions. The enzyme itself does not undergo any permanent chemical change during this process, but rather acts as a catalyst to lower the activation energy required for the reaction to occur.

Oxidoreductases are classified and named based on the type of electron donor or acceptor involved in the reaction. For example, oxidoreductases that act on the CH-OH group of donors are called dehydrogenases, while those that act on the aldehyde or ketone groups are called oxidases. Other examples include reductases, peroxidases, and catalases.

Understanding the function and regulation of oxidoreductases is important for understanding various physiological processes and developing therapeutic strategies for diseases associated with impaired redox homeostasis, such as cancer, neurodegenerative disorders, and cardiovascular disease.

Glutathione reductase (GR) is an enzyme that plays a crucial role in maintaining the cellular redox state. The primary function of GR is to reduce oxidized glutathione (GSSG) to its reduced form (GSH), which is an essential intracellular antioxidant. This enzyme utilizes nicotinamide adenine dinucleotide phosphate (NADPH) as a reducing agent in the reaction, converting it to NADP+. The medical definition of Glutathione Reductase is:

Glutathione reductase (GSR; EC 1.8.1.7) is a homodimeric flavoprotein that catalyzes the reduction of oxidized glutathione (GSSG) to reduced glutathione (GSH) in the presence of NADPH as a cofactor. This enzyme is essential for maintaining the cellular redox balance and protecting cells from oxidative stress by regenerating the active form of glutathione, a vital antioxidant and detoxifying agent.

Ferredoxin-NADP Reductase (FDNR) is an enzyme that catalyzes the electron transfer from ferredoxin to NADP+, reducing it to NADPH. This reaction plays a crucial role in several metabolic pathways, including photosynthesis and nitrogen fixation.

In photosynthesis, FDNR is located in the stroma of chloroplasts and receives electrons from ferredoxin, which is reduced by photosystem I. The enzyme then transfers these electrons to NADP+, generating NADPH, which is used in the Calvin cycle for carbon fixation.

In nitrogen fixation, FDNR is found in the nitrogen-fixing bacteria and receives electrons from ferredoxin, which is reduced by nitrogenase. The enzyme then transfers these electrons to NADP+, generating NADPH, which is used in the reduction of nitrogen gas (N2) to ammonia (NH3).

FDNR is a flavoprotein that contains a FAD cofactor and an iron-sulfur cluster. The enzyme catalyzes the electron transfer through a series of conformational changes that bring ferredoxin and NADP+ in close proximity, allowing for efficient electron transfer.

Thioredoxin-disulfide reductase (Txnrd, TrxR) is an enzyme that belongs to the pyridine nucleotide-disulfide oxidoreductase family. It plays a crucial role in maintaining the intracellular redox balance by reducing disulfide bonds in proteins and keeping them in their reduced state. This enzyme utilizes NADPH as an electron donor to reduce thioredoxin (Trx), which then transfers its electrons to various target proteins, thereby regulating their activity, protein folding, and antioxidant defense mechanisms.

Txnrd is essential for several cellular processes, including DNA synthesis, gene expression, signal transduction, and protection against oxidative stress. Dysregulation of Txnrd has been implicated in various pathological conditions, such as cancer, neurodegenerative diseases, and inflammatory disorders. Therefore, understanding the function and regulation of this enzyme is of great interest for developing novel therapeutic strategies.

Cytochrome reductases are a group of enzymes that play a crucial role in the electron transport chain, a process that occurs in the mitochondria of cells and is responsible for generating energy in the form of ATP (adenosine triphosphate). Specifically, cytochrome reductases are responsible for transferring electrons from one component of the electron transport chain to another, specifically to cytochromes.

There are several types of cytochrome reductases, including NADH dehydrogenase (also known as Complex I), succinate dehydrogenase (also known as Complex II), and ubiquinone-cytochrome c reductase (also known as Complex III). These enzymes help to facilitate the flow of electrons through the electron transport chain, which is essential for the production of ATP and the maintenance of cellular homeostasis.

Defects in cytochrome reductases can lead to a variety of mitochondrial diseases, which can affect multiple organ systems and may be associated with symptoms such as muscle weakness, developmental delays, and cardiac dysfunction.

Flavin-Adenine Dinucleotide (FAD) is a coenzyme that plays a crucial role in various metabolic processes, particularly in the electron transport chain where it functions as an electron carrier in oxidation-reduction reactions. FAD is composed of a flavin moiety, riboflavin or vitamin B2, and adenine dinucleotide. It can exist in two forms: an oxidized form (FAD) and a reduced form (FADH2). The reduction of FAD to FADH2 involves the gain of two electrons and two protons, which is accompanied by a significant conformational change that allows FADH2 to donate its electrons to subsequent components in the electron transport chain, ultimately leading to the production of ATP, the main energy currency of the cell.

Flavins are a group of naturally occurring organic compounds that contain a characteristic isoalloxazine ring, which is a tricyclic aromatic structure. The most common and well-known flavin is flavin adenine dinucleotide (FAD), which plays a crucial role as a coenzyme in various biological oxidation-reduction reactions. FAD accepts electrons and hydrogens to form the reduced form, flavin adenine dinucleotide hydride (FADH2). Another important flavin is flavin mononucleotide (FMN), which is derived from FAD and functions similarly as a coenzyme. Flavins are yellow in color and can be found in various biological systems, including animals, plants, and microorganisms. They are involved in several metabolic pathways, such as the electron transport chain, where they contribute to energy production.

NADH, NADPH oxidoreductases are a class of enzymes that catalyze the redox reaction between NADH or NADPH and various electron acceptors. These enzymes play a crucial role in cellular metabolism by transferring electrons from NADH or NADPH to other molecules, which is essential for many biochemical reactions.

NADH (nicotinamide adenine dinucleotide hydrogen) and NADPH (nicotinamide adenine dinucleotide phosphate hydrogen) are coenzymes that act as electron carriers in redox reactions. They consist of a nicotinamide ring, which undergoes reduction or oxidation by accepting or donating electrons and a proton (H+).

NADH, NADPH oxidoreductases are classified based on their structure and mechanism of action. Some examples include:

1. Dehydrogenases: These enzymes catalyze the oxidation of NADH or NADPH to NAD+ or NADP+ while reducing an organic substrate. Examples include lactate dehydrogenase, alcohol dehydrogenase, and malate dehydrogenase.
2. Oxidases: These enzymes catalyze the oxidation of NADH or NADPH to NAD+ or NADP+ while reducing molecular oxygen (O2) to water (H2O). Examples include NADH oxidase and NADPH oxidase.
3. Reductases: These enzymes catalyze the reduction of various electron acceptors using NADH or NADPH as a source of electrons. Examples include glutathione reductase, thioredoxin reductase, and nitrate reductase.

Overall, NADH, NADPH oxidoreductases are essential for maintaining the redox balance in cells and play a critical role in various metabolic pathways, including energy production, detoxification, and biosynthesis.

Other names in common use include NAD(P)H-FMN reductase, NAD(P)H-dependent FMN reductase, NAD(P)H:FMN oxidoreductase, NAD(P)H: ... flavin oxidoreductase, NAD(P)H2 dehydrogenase (FMN), NAD(P)H2:FMN oxidoreductase, SsuE, riboflavin mononucleotide reductase, ... In enzymology, an FMN reductase (EC 1.5.1.29) is an enzyme that catalyzes the chemical reaction FMNH2 + NAD(P)+ ⇌ {\ ... reductase, flavin mononucleotide reductase, and riboflavine mononucleotide reductase. Duane W, Hastings JW (1975). "Flavin ...
... (EC 1.5.1.42, NADH-FMN reductase) is an enzyme with systematic name FMNH2:NAD+ oxidoreductase. This enzyme ... Gerlo E, Charlier J (September 1975). "Identification of NADH-specific and NADPH-specific FMN reductases in Beneckea harveyi" ( ... FMN+reductase+(NADH) at the U.S. National Library of Medicine Medical Subject Headings (MeSH) Portal: Biology (Articles with ... Izumoto Y, Mori T, Yamamoto K (April 1994). "Cloning and nucleotide sequence of the gene for NADH:FMN oxidoreductase from ...
... (EC 1.5.1.38, FRP, flavin reductase P, SsuE) is an enzyme with systematic name FMNH2:NADP+ oxidoreductase ... Gerlo E, Charlier J (September 1975). "Identification of NADH-specific and NADPH-specific FMN reductases in Beneckea harveyi" ( ... FMN+reductase+(NADPH) at the U.S. National Library of Medicine Medical Subject Headings (MeSH) Portal: Biology (Articles with ... Tanner JJ, Lei B, Tu SC, Krause KL (October 1996). "Flavin reductase P: structure of a dimeric enzyme that reduces flavin". ...
... (EC 1.5.1.39, FRG) is an enzyme with systematic name FMNH2:NAD(P)+ oxidoreductase. This enzyme ... FMN+reductase+(NAD(P)H) at the U.S. National Library of Medicine Medical Subject Headings (MeSH) Portal: Biology (EC 1.5.1). ... H+ This enzyme contains FMN. Watanabe H, Hastings JW (May 1982). "Specificities and properties of three reduced pyridine ... nucleotide-flavin mononucleotide reductases coupling to bacterial luciferase". Molecular and Cellular Biochemistry. 44 (3): 181 ...
PDR is a single protein comprising FMN-binding reductase and plant-type ferredoxin domains. Thus, the electron transfer in ARHD ... In benzoate and toluate 1,2-dioxygenase systems, a single protein containing reductase and Rieske-type ferredoxin domains ... In the phthalate 4,5-dioxygenase system, phthalate dioxygenase reductase (PDR) has the same function. ...
"Three-dimensional structure of NADPH-cytochrome P450 reductase: Prototype for FMN- and FAD-containing enzymes". Proceedings of ... Yasukochi, Y; Masters, B S (1976). "Some properties of a detergent-solubilized NADPH-cytochrome c(cytochrome P-450) reductase ... Yasukochi, Y; Masters, B S (1976). "Some properties of a detergent-solubilized NADPH-cytochrome c(cytochrome P-450) reductase ... As a graduate student she characterized cytochrome P450 reductase (NADPH-cytochrome P450 oxidoreductase). She went on to ...
"Three-dimensional structure of NADPH-cytochrome P450 reductase: prototype for FMN- and FAD-containing enzymes". Proc. Natl. ... Other names include cytochrome P450 reductase, ferrihemoprotein P-450 reductase, and NADPH-dependent cytochrome c reductase. As ... It has 2 cofactors: FAD, and FMN. This enzyme belongs to the family of oxidoreductases, specifically those acting on NADH or ... Haas E, Horecker BL, Hogness TR (1940). "The enzymatic reduction of cytochrome c, cytochrome c reductase". J. Biol. Chem. 136: ...
Estrada DF, Laurence JS, Scott EE (February 2016). "Cytochrome P450 17A1 Interactions with the FMN Domain of Its Reductase as ...
"Three-dimensional structure of NADPH-cytochrome P450 reductase: prototype for FMN- and FAD-containing enzymes". Proceedings of ... Cytochrome P450s normally are complemented by either a cytochrome P450 reductase or a ferredoxin and ferredoxin reductase; its ... and a three-domain reductase (encoded by the gcoB gene) complexed with three cofactors (2Fe-2S, FAD, and NADH). GcoA and GcoB ... "Redox-linked domain movements in the catalytic cycle of cytochrome p450 reductase". Structure. 21 (9): 1581-9. doi:10.1016/j. ...
FMN/Fd/P450 systems originally found in Rhodococcus species, in which a FMN-domain-containing reductase is fused to the CYP. ... Substrate binding induces electron transfer from NAD(P)H via cytochrome P450 reductase or another associated reductase. ... Bacterial P450 systems which employ a ferredoxin reductase and a ferredoxin to transfer electrons to P450. CYB5R/cyb5/P450 ... A second electron is transferred, from either cytochrome P450 reductase, ferredoxins, or cytochrome b5, reducing the Fe-O2 ...
... (EC 1.5.1.41, NAD(P)H-FMN reductase, Fre) is an enzyme with systematic name riboflavin:NAD(P)+ ... A ferric iron reductase participating in the generation of the free radical of ribonucleotide reductase". The Journal of ... Therefore, in the proposed mechanism the flavin reductase first binds NAD(P)H and stabilizes the release of a hydride3. Next, ... If this mechanism is indeed correct, it suggests that the reduction of flavin by flavin reductase is dependent on the enzyme ...
... is a dimeric flavoenzyme comprising two 8-fold α/β-barrel domains, each with a non-covalently bound FMN ... The prosthetic group FMN serves as a cofactor in the redox reaction catalyzed by morphinone reductase. In the reduction of ... Morphinone reductase is an enzyme which catalyzes the NADH-dependent saturation of the carbon-carbon double bond of morphinone ... This saturation reaction is assisted by a FMN cofactor and the enzyme is a member of the α/β-barrel flavoprotein family. The ...
... may refer to: Riboflavin reductase (NAD(P)H), an enzyme FMN reductase, an enzyme This set ...
FMN domain, ferredoxin or cytochrome b5 transfer electrons between the flavin reductase (protein or domain) and P450. While ... and FMN-containing enzyme known as cytochrome P450 reductase (CPR; EC 1.6.2.4). Microsomal CPR is membrane-bound protein that ... the N-terminal P450 domain is fused to the reductase domain that shows sequence similarity to phthalate dioxygenase reductase ... The general scheme of electron flow in this system appears to be: Nitric oxide reductase (P450nor) is a P450 enzyme involved in ...
... may refer to: Family Readiness Group in the United States Army Federal Republic of Germany West Germany FMN reductase (NAD( ...
FMN reductase (NADPH), UvrABC system protein C, sensor histidine kinase YycG, hypothetical proteins, ribonuclease Y, cell ...
It has 2 cofactors: FAD, and FMN. FRIEDMANN HC, VENNESLAND B (1958). "Purification and properties of dihydro-orotic ... In enzymology, an orotate reductase (NADH) (EC 1.3.1.14) is an enzyme that catalyzes the chemical reaction (S)-dihydroorotate ... This enzyme is also called orotate reductase (NADH). This enzyme participates in pyrimidine metabolism. ...
The ferric reductase reaction requires NAD(P)H and FMN. This activity is intriguing, as haem cleavage in the foetus produces ... Flavin reductase/biliverdin-IXbeta reductase has also been shown to exhibit ferric reductase activity, with an apparent K(m) of ... Shalloe F, Elliott G, Ennis O, Mantle TJ (Jun 1996). "Evidence that biliverdin-IX beta reductase and flavin reductase are ... Yamaguchi T, Komoda Y, Nakajima H (Sep 1994). "Biliverdin-IX alpha reductase and biliverdin-IX beta reductase from human liver ...
Matsumoto K, Mukai Y, Ogata D, Shozui F, Nduko JM, Taguchi S, Ooi T (2009). "Characterization of thermostable FMN-dependent ... Other names in common use include: azo reductase, azoreductase, azo-dye reductase, dibromopropylaminophenylazobenzoic ... NC-reductase, new coccinea (NC)-reductase, nicotinamide adenine dinucleotide (phosphate) azoreductase, orange I azoreductase, ... Azobenzene reductase also known as azoreductase (EC 1.7.1.6) is an enzyme that catalyzes the chemical reaction: N,N-dimethyl-1, ...
... cluster relay of the small hydrogenase subunit and the reductase module, then to another FMN-b cofactor and finally to NAD+. ... hydrogenase and the other two subunits comprising a reductase module similar to the one of Complex I. The [Ni-Fe] active site ... oxidized hydrogen gas which transfers electrons to a FMN-a cofactor, then to a [Fe-S] ...
... and FMN-containing enzyme NADPH:cytochrome P450 reductase The general scheme of electron flow in the POR/P450 system is: NADPH ... aldehyde dehydrogenase Monoamine oxidase Co-oxidation by peroxidases NADPH-cytochrome P450 reductase Cytochrome P450 reductase ... P450 reductase, POR, CPR, CYPOR, is a membrane-bound enzyme required for electron transfer to cytochrome P450 in the microsome ... FAD → FMN → P450 → O2 Reduced (ferrous) cytochrome P450 During reduction reactions, a chemical can enter futile cycling, in ...
FMN reductase (NADPH), NADPH-dependent FMN reductase, NADPH-flavin reductase, NADPH-FMN reductase, NADPH-specific FMN reductase ... The ping pong mechanism is shown with NADPH binding first and leaving as NADP+ before FMN is bound by Flavin Reductase. The ... Flavin reductase a class of enzymes. There are a variety of flavin reductases, (i.e. FRP, FRE, FRG, etc.) which bind free ... Flavin reductases exist in a variety of organisms, including animals and bacteria. In luminous organisms, flavin reductase is ...
The FMN-binding domain is similar to the structure of FMN-containing protein flavodoxin, whereas the FAD-binding domain and ... sulfite reductase (EC 1.8.1.2), and methionine synthase reductase (EC 1.16.1.8).[citation needed] The 3D crystal structure of ... Cytochrome+P450+Reductase at the U.S. National Library of Medicine Medical Subject Headings (MeSH) GeneReviews/NCBI/NIH/UW ... The molecule is composed of four structural domains: the FMN-binding domain, the connecting domain, the FAD-binding domain, and ...
The two electrons on reduced FAD (FADH2) are transferred one at a time to FMN and then a single electron is passed from FMN to ... The structures of the reductase of the microsomal versus reductase of the mitochondrial P450 systems are completely different ... Two classes of CS are known, both of which require FMN, but are divided on their need for NADPH as a reducing agent. The ... A flavoprotein is a protein that contains a flavin group, which may be in the form of FAD or flavin mononucleotide (FMN). Many ...
In addition to NADPH, E. Coli DECR requires a set of FAD, FMN and iron-sulfur cluster molecules to complete the electron ... Beta oxidation 2,4-dienoyl-CoA reductase 1 "Entrez Gene: 2,4-dienoyl CoA reductase 1, mitochondrial". Koivuranta KT, Hakkola EH ... 4-dienoyl-CoA reductase: enzyme-ligand interactions in a distinctive short-chain reductase active site". The Journal of ... Hua T, Wu D, Ding W, Wang J, Shaw N, Liu ZJ (August 2012). "Studies of human 2,4-dienoyl CoA reductase shed new light on ...
The FMN cofactor is first reduced by NADPH, the substrate is then bound, and finally the substrate is reduced by a hydride ... 12-oxophytodienoate reductase (OPRs) is an enzyme of the family of Old Yellow Enzymes (OYE). OPRs are grouped into two groups: ... 12-oxophytodienoate reductase structure resembles OYE enzymes and has been elucidated by x-ray crystal structures. The cDNA ... 12-oxophytodienoate reductase has also been shown to practice self-inhibition by dimerization. This is the only flavoprotein ...
3 H+ Sulfite reductase is an iron flavoprotein (FAD and FMN). Hilz H, Kittler M, Knape G (1959). "[The reduction of sulfate in ... reductase, NADPH-sulfite reductase, NADPH-dependent sulfite reductase, H2S-NADP oxidoreductase, sulfite reductase (NADPH2)) is ... Sulfite reductase (NADPH) (EC 1.8.1.2, sulfite (reduced nicotinamide adenine dinucleotide phosphate) ... Yoshimoto A, Sato R (April 1968). "Studies on yeast sulfite reductase. I. Purification and characterization". Biochimica et ...
... which requires FMN. An enzyme involved in folate metabolism, 5,10-methylenetetrahydrofolate reductase, requires FAD to form the ... Riboflavin is reversibly converted to FMN and then FAD. From riboflavin to FMN is the function of zinc-requiring riboflavin ... Riboflavin, FMN, and FAD are involved in the metabolism of niacin, vitamin B6, and folate. The synthesis of the niacin- ... From FMN to FAD is the function of magnesium-requiring FAD synthase; the reverse is accomplished by a pyrophosphatase. FAD ...
The reductase protein is responsible for transfer of an electron from a reduced FMN cofactor to the inactive Cob(II), which ... Methionine synthase reductase (MTRR) or methylene-tetrahydrofolate reductase (MTHFR) deficiencies can also result in the ... In humans, the enzyme is reduced in this process by methionine synthase reductase (MTRR), which consists of flavodoxin-like and ... The reactivation domain binds SAM and is the site of interaction with flavodoxin or Methionine Synthase Reductase during the ...
It has 3 cofactors: iron, FMN, and Iron-sulfur. Batie CJ, LaHaie E, Ballou DP (1987). "Purification and characterization of ... phthalate oxygenase and phthalate oxygenase reductase from Pseudomonas cepacia". J. Biol. Chem. 262 (4): 1510-8. PMID 3805038. ...
Other names in common use include NAD(P)H-FMN reductase, NAD(P)H-dependent FMN reductase, NAD(P)H:FMN oxidoreductase, NAD(P)H: ... flavin oxidoreductase, NAD(P)H2 dehydrogenase (FMN), NAD(P)H2:FMN oxidoreductase, SsuE, riboflavin mononucleotide reductase, ... In enzymology, an FMN reductase (EC 1.5.1.29) is an enzyme that catalyzes the chemical reaction FMNH2 + NAD(P)+ ⇌ {\ ... reductase, flavin mononucleotide reductase, and riboflavine mononucleotide reductase. Duane W, Hastings JW (1975). "Flavin ...
While FMN is the preferred substrate, FAD can also be used with much lower activity. ...
Family c.23.5.4: NADPH-dependent FMN reductase [89590] (5 proteins). Pfam PF03358. ... PDB Description: Crystal Structure of the Putative NADPH-dependent Azobenzene FMN-Reductase YhdA from Bacillus subtilis, ... d2gswc_ c.23.5.4 (C:) Azobenzene reductase {Bacillus subtilis [TaxId: 224308]} ...
Deep tunneling dominates the biologically important hydride transfer reaction from NADH to FMN in morphinone reductase. J Pang ...
The model system is E. coli nitro/quinone reductase NfsA, a promiscuous FMN-dependent oxidoreductase that reduces toxic ... We were able to achieve both these goals by employing the Escherichia coli nitro/quinone reductase NfsA as a new model system ... For clarity, only one of the two FMN-binding active sites in the enzyme homodimer is portrayed. (B) Summary of the amino acid ... 2004) Mechanism of chromate reduction by the Escherichia coli protein, NfsA, and the role of different chromate reductases in ...
FMN Reductase. Nitric-Oxide Synthase. Nitric Oxide Synthase. Prostaglandin-Endoperoxide Synthase. Prostaglandin-Endoperoxide ...
FMN Reductase. Nitric-Oxide Synthase. Nitric Oxide Synthase. Prostaglandin-Endoperoxide Synthase. Prostaglandin-Endoperoxide ...
FMN Reductase. Nitric-Oxide Synthase. Nitric Oxide Synthase. Prostaglandin-Endoperoxide Synthase. Prostaglandin-Endoperoxide ...
FMN Reductase. Nitric-Oxide Synthase. Nitric Oxide Synthase. Prostaglandin-Endoperoxide Synthase. Prostaglandin-Endoperoxide ...
FMN Reductase. Nitric-Oxide Synthase. Nitric Oxide Synthase. Prostaglandin-Endoperoxide Synthase. Prostaglandin-Endoperoxide ...
FMN Reductase. Nitric-Oxide Synthase. Nitric Oxide Synthase. Prostaglandin-Endoperoxide Synthase. Prostaglandin-Endoperoxide ...
FMN Reductase. Nitric-Oxide Synthase. Nitric Oxide Synthase. Prostaglandin-Endoperoxide Synthase. Prostaglandin-Endoperoxide ...
FMN Reductase. Nitric-Oxide Synthase. Nitric Oxide Synthase. Prostaglandin-Endoperoxide Synthase. Prostaglandin-Endoperoxide ...
FMN Reductase. Nitric-Oxide Synthase. Nitric Oxide Synthase. Prostaglandin-Endoperoxide Synthase. Prostaglandin-Endoperoxide ...
FMN Reductase. Nitric-Oxide Synthase. Nitric Oxide Synthase. Prostaglandin-Endoperoxide Synthase. Prostaglandin-Endoperoxide ...
FMN Reductase. Nitric-Oxide Synthase. Nitric Oxide Synthase. Prostaglandin-Endoperoxide Synthase. Prostaglandin-Endoperoxide ...
Fmn Reductase * Saccharomyces Cerevisiae * Reverse Transcriptase Polymerase Chain Reaction * Transcription Factors * ...
ReductaseNitric OxideCopperHydroxylaminesGlutathione ReductaseFMN ReductaseThioredoxin-Disulfide ReductaseNitrous OxideNADPH- ... Nitrate reductase (NADH) Nitrate reductase (NADPH) Nitrate reductase (NAD(P)H) Nitrate reductase (quinone) Nitrite reductase ... Nitrite reductase may also refer to: Nitrite reductase (NO-forming) Nitrite reductase (NAD(P)H) Cytochrome c nitrite reductase ... Nitrite reductase (NO-forming). ... reductase, methyl viologen-nitrite reductase, nitrite reductase (cytochrome, and NO-forming ...
FMN reductase activity GO:0008752 * gibberellin 3-beta-dioxygenase activity GO:0016707 ...
Funciton: NADPH-dependent FMN reductase Locus tag: Smlt2585. Name: PF08908. Funciton: Protein of unknown function DUF1852 ...
flavin reductase domain protein FMN-binding YP_002551574 normal 1 n/a Acidovorax ebreus TPSY Bacteria -. ... NADPH-dependent FMN reductase YP_002551533 normal 1 n/a Acidovorax ebreus TPSY Bacteria -. ... pyridoxamine 5-phosphate oxidase-related FMN-binding YP_002551506 normal 0.0687493 n/a Acidovorax ebreus TPSY Bacteria -. ...
FMN_red. 2.0e-15. 17. 146. 131. + NADPH-dependent FMN reductase. ...
","Putative reductase [Ensembl]. NADPH-dependent FMN reductase [Interproscan].","protein_coding" "CCL20332","No alias"," ... ","Putative FMN-binding protein [Ensembl]. FMN-binding domain [Interproscan].","protein_coding" "CCL17890","No alias"," ... ","putative NAD(P)-binding oxidoreductase [Ensembl]. Aldo/keto reductase family [Interproscan].","protein_coding" "AAC74503"," ... ","putative oxidoreductase [Ensembl]. Enoyl-(Acyl carrier protein) reductase [Interproscan].","protein_coding" "AAC75437","lpxP ...
Multiple membrane-bound heterodisulfide reductase (DsrMK) could promote both energy-conserving and non-energy-conserving ... and a novel nitrate reductase-associated respiratory complex was induced specifically in the presence of sulfate. A potential ... due to the constitutive expression of qmoABC and lack of putative FAD/FMN binding domains in "NapH" questions that the nitrate ... J. Kunow, B. Schwörer, K. O. Stetter, and R. K. Thauer, "A F420-dependent NADP reductase in the extremely thermophilic sulfate- ...
NADPH-dependent FMN reductase family protein. 2e+0. At4g23690. disease resistance-responsive family protein / dirigent family ... Encodes NAD(P)H:quinone reductase which is an FMN binding protein that catalyzes the reduction of quinone substrates to ...
NADPH-dependent FMN reductase (predicted) [Source:PomBase;Acc:SPCC4B3.06c]. Location. Chromosome III: 1,163,990-1,165,874 ...
Family: NADPH-dependent FMN reductases family. *Sequence: FASTA. *Cross-database IDs: Link ...
Ortholog function: Enoyl-[acyl-carrier-protein] reductase [FMN] (EC 1.3.1.9) Streptococcus agalactiae 2603V/R SAG0346 -37. 6.2 ...
oxidoreductase, NAD(P)H-FMN and ferric iron reductase (RefSeq). 295, 372. ...
FMN/Fd/P450 systems originally found in Rhodococcus sp. in which a FMN-domain-containing reductase is fused to the CYP. ... H via cytochrome P450 reductase or another associated reductase[8]. This takes place by way of the electron transfer chain, as ... Cytochrome b5 (cyb5) can also contribute reducing power to this system after being reduced by cytochrome b5 reductase (CYB5R). ... 4: A second electron is transferred via the electron-transport system, either from cytochrome P450 reductase, ferredoxins, or ...
  • In enzymology, an FMN reductase (EC 1.5.1.29) is an enzyme that catalyzes the chemical reaction FMNH2 + 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+. (wikipedia.org)
  • These are complex I- NADH/NADPH: CoQ reductase, complex II- Succinate: CoQ reductase, complex III- Reduced CoQ (CoQH₂): cytochrome c reductase, complex IV- Cytochrome c oxidase, complex V- ATPase (ATP synthesizing system). (sciencequery.com)
  • Broad specificity oxidoreductase that catalyzes the NADPH-dependent reduction of a variety of flavins, such as riboflavin, FAD or FMN, biliverdins, methemoglobin and PQQ (pyrroloquinoline quinone). (lifescience-market.com)
  • Can also reduce the complexed Fe(3+) iron to Fe(2+) in the presence of FMN and NADPH. (lifescience-market.com)
  • The results showed that if the FMN, in the isolated FMN domain, is assumed to be fully accessible, then it is 100% accessible in the CaM-bound enzyme, 45% accessible in the uncompleted enzyme and only 3% accessible in the NADPH-bound nNOSrd in the absence of CaM. (ndltd.org)
  • Kinetic and Structural Basis of Reactivity of Pentaerythritol Tetranitrate Reductase with Nadph,2-Cyclohexenone Nitroesters and Nitroaromatic Explosives. (expasy.org)
  • These cysteines are located within regions known to bind flavin mononucleotide (FMN), flavin adenine dinucleotide (FAD), and nicotinamide adenine dinucleotide (NADPH) although from our studies their functional significance is unclear. (elsevierpure.com)
  • Encodes NAD(P)H:quinone reductase which is an FMN binding protein that catalyzes the reduction of quinone substrates to hydroquinones.The enzyme activity was confirmed by in vitro assay. (or.jp)
  • Enoyl-(Acyl carrier protein) reductase [Interproscan]. (ntu.edu.sg)
  • The encoded protein shares a high degree of homology to clostridial FMN- and FAD-dependent 2-enoate reductases, including the cinnamic acid reductase proposed to be involved in amino acid metabolism in proteolytic clostridia. (microbiologyresearch.org)
  • [ 14 ] In the stomach, gastric acidity cleaves most of the coenzyme forms of riboflavin (FAD and FMN) from the protein. (medscape.com)
  • 1], The proposed pathway for electron transport prior to ubiquinone reduction is as follows: NADH - FMN - N3 - N1b - N4 - N5 - N6a - N6b - N2 - Q, where Nx is a labelling convention for iron sulfur clusters. (gowebamerica.com)
  • Riboflavin consisting of two important cofactors, flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), which are involved in multiple oxidative-reduction processes and energy metabolism. (bioseek.eu)
  • Vitamin B2, or riboflavin, is a water-soluble vitamin most commonly found in the body in the form of the flavocoenzymes flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), the latter being most abundant. (medscape.com)
  • 7] FAD is also a coenzyme needed for the functioning of the antioxidant enzyme glutathione reductase in its protection of cells against oxidative stresses, allowing for the measurement of the enzyme's activity in red blood cells to be among the methods for the assessment of riboflavin nutritional status. (medscape.com)
  • Two derivatives, riboflavin 5' phosphate (flavin mononucleotide [FMN]) and riboflavin 5' adenosine diphosphate (flavin adenine dinucleotide [FAD]), are the coenzymes that unite with specific apoenzyme proteins to form flavoprotein enzymes. (medscape.com)
  • We selected the Escherichia coli nitro/quinone reductase NfsA for chloramphenicol detoxification by simultaneously randomising eight active-site residues and interrogating ~250,000,000 reconfigured variants. (elifesciences.org)
  • However, kinetic parameters show that it is less efficient than the biliverdin reductase Rv2074 and suggest biliverdin-IXalpha is unlikely to be the native substrate of Rv1155 , which probably catalyzes the reduction of an alternative molecule in vivo. (string-db.org)
  • In order to investigate the CaM activation mechanism of nNOS, the effect of the conformational changes of nNOSrd and the binding of NADP(H) on the redox potential of the flavins, cofactors were assessed for the isolated FAD and FMN sub-domains by OTTLE potentiometry. (ndltd.org)
  • Binds coenzyme F420, but does not bind FMN or other flavins. (string-db.org)
  • FMN-binding split barrel-related, Pyridoxamine 5'-phosphate oxidase, Rv1155 _F420: PPOX class probable F420-dependent enzyme. (string-db.org)
  • Aldo/keto reductase family [Interproscan]. (ntu.edu.sg)
  • In addition, cysteine residues within the reductase domain were identified as undergoing S-nitrosylation. (elsevierpure.com)
  • A hypothetical 2-enoate reductase gene, fldZ , was identified in Clostridium sporogenes DSM 795. (microbiologyresearch.org)
  • F420H(2)-dependent reductase able to catalyze the reduction of biliverdin-IXalpha to bilirubin-IXalpha in vitro. (string-db.org)
  • To date, research has been focussed primarily on Old Yellow Enzyme-like proteins, due to their ease of handling, whereas 2-enoate reductases from clostridia have received much less attention, because of their oxygen sensitivity and a lack of suitable expression systems. (microbiologyresearch.org)
  • may control both electron transfers between the FAD and FMN and from FMN to heme by modulating the potential of the FAD hydroquinone. (ndltd.org)
  • The accessibility of the FMN cofactor to the heme was assessed. (ndltd.org)
  • This suggests that the binding of CaM is responsible for a structural reorganisation of nNOS rd that "unlocks" the conformation of the enzyme and enables the FMN sub-domain motion in order to shuttle an electron from FAD cofactor to the heme. (ndltd.org)
  • Analysis of every possible intermediate of the two best chloramphenicol reductases revealed complex epistatic interactions. (elifesciences.org)
  • The bifunctional CODH ( cdhAB-2 ) is predicted to play an ubiquitous role in the metabolism of CO, and a novel nitrate reductase-associated respiratory complex was induced specifically in the presence of sulfate. (hindawi.com)
  • While FMN is the preferred substrate, FAD can also be used with much lower activity. (expasy.org)
  • Related tests: Erythrocyte glutathione reductase activity assay, expressed a ratio of tests performed with and without added without flavin adenine dinucleotide. (medscape.com)
  • The results showed that the presence of the FAD/FMN sub-domain interface does not alter the thermodynamic properties of the redox couples involved in the catalysis. (ndltd.org)
  • The availability of an expression system for this recombinant clostridial 2-enoate reductase will facilitate future characterisation of this unusual class of 'ene'-reductases, and expand the biocatalytic toolbox available for enantioselective hydrogenation of carbon-carbon double bonds. (microbiologyresearch.org)
  • Ene'-reductases have attracted significant attention for the preparation of chemical intermediates and biologically active products. (microbiologyresearch.org)
  • It is proposed that S. enterica serovar Typhimurium LT2 may not have a cob(III)alamin reductase enzyme and that, in vivo, nonadenosylated cobalamin and other corrinoids are maintained as co(II)rrinoids by reduced flavin nucleotides generated by Fre and other flavin oxidoreductases. (nih.gov)
  • The two-component alkanesulfonate monooxygenase system from Escherichia coli is comprised of an FMN reductase (SsuE) and a monooxygenase enzyme (SsuD) that together catalyze the oxidation of alkanesulfonate to the corresponding aldehyde and sulfite products. (auburn.edu)
  • These results suggest that both the SsuD enzyme and alkanesulfonate substrate are required to ensure that the FMN reductases reaction proceeds to form the ternary complex with the subsequent generation of reduced flavin. (auburn.edu)
  • The data showthat the FMN attachment does not require assembly of the enzyme and areconsistent with the unusual threonine attachment site. (embl-heidelberg.de)
  • The enzyme consists of linked oxygenase and reductase domains. (cathdb.info)
  • The eukaryotic enzyme binds FAD, FMN, heme (iron protoporphyrin IX) and tetrahydrobiopterin, and its two domains are linked via a regulatory calmodulin-binding domain. (cathdb.info)
  • The reductase domain of the enzyme from the bacterium Sorangium cellulosum utilizes a [2Fe-2S] cluster to transfer the electrons from NADPH to the active center. (cathdb.info)
  • The enzyme from Escherichia coli contains FAD, FMN, and an [4Fe-4S] iron sulfur cluster. (expasy.org)
  • 8] FAD is also a coenzyme needed for the functioning of the antioxidant enzyme glutathione reductase in its protection of cells against oxidative stresses, allowing for the measurement of the enzyme's activity in red blood cells to be among the methods for the assessment of riboflavin nutritional status. (medscape.com)
  • Analysis of cytochrome c reduction rates measured within the first catalytic turnover revealed that the rate of conformational change to the FMN-deshielded state differed between eNOSr and nNOSr and was rate-limiting for either CaM-free enzyme. (montclair.edu)
  • Dithiothreitol protects the FAD dependent cytochrome c reductase activity against inactivation by free radicals. (tmc.edu)
  • Despite their structural similarity, endothelial NOS (eNOS) has a 6-fold lower NO synthesis activity and 6-16-fold lower cytochrome c reductase activity than neuronal NOS (nNOS), implying significantly different electron transfer capacities. (montclair.edu)
  • Related tests: Erythrocyte glutathione reductase activity assay, expressed using a ratio of tests performed with and without added flavin adenine dinucleotide. (medscape.com)
  • A stable and sensitive measure of riboflavin deficiency is the erythrocyte glutathione reductase activity coefficient (EGRAC), which is based on the ratio between this enzyme's in vitro activity in the presence of FAD to that without added FAD [ 1 , 6 , 7 ]. (nih.gov)
  • NDOR1-CIAPIN1 are also required for the assembly of the diferric tyrosyl radical cofactor of ribonucleotide reductase (RNR), probably by providing electrons for reduction during radical cofactor maturation in the catalytic small subunit (By similarity). (nih.gov)
  • In contrast, calmodulin (CaM)-free eNOSr favored the FMN-shielded (electron-accepting) conformation over the FMN-deshielded (electron-donating) conformation to a much greater extent than did CaM-free nNOSr when the bound FMN cofactor was poised in each of its three possible oxidation states. (montclair.edu)
  • Expression and mutagenesis of the NqrC subunit of the NQR respiratoryNa(+) pump from Vibrio cholerae with covalently attached FMN. (embl-heidelberg.de)
  • Thus, subunit association must be required for FMN binding and catalysis. (wikidoc.org)
  • Most eukaryotic microsomes have 2-component systems (class II/class E) - NADPH:P450 reductase (FAD and FMN-containing flavoprotein) and P450. (embl.de)
  • Purified recombinant PduS is shown to be a flavoprotein with a non-covalently bound FMN that also contains two coupled [4Fe-4S] centres. (uea.ac.uk)
  • An iron-sulfur flavoprotein, containing two covalently bound molecules of FMN, one noncovalently bound FAD, one riboflavin, and one [2Fe-2S] cluster. (enzyme-database.org)
  • Results from isotope studies with the [4(R)-2H]NADPH substrate demonstrates the rate-limiting step in flavin reduction is electron transfer from NADPH to FMN. (auburn.edu)
  • All are dimeric enzymes that shuttle electrons from NADPH, which binds to a C-terminal reductase domain, through the flavins FAD and FMN to the oxygenase domain of the other monomer to enable the BH4-dependent reduction of heme bound oxygen for insertion into the substrate, L-arginine. (guidetopharmacology.org)
  • Electrons required for verdoheme oxidation can be transferred through a pathway not involving FMN. (nih.gov)
  • Upon calcium-induced calmodulin binding, the reductase and oxygenase domains form a complex, allowing electrons to flow from NADPH via FAD and FMN to the active center. (cathdb.info)
  • NOSs are flavo-hemo proteins, with two flavin molecules (FAD and FMN) and one heme per monomer, which require the binding of calcium/calmodulin (Ca 2+ /CaM) to produce NO. It is therefore important to understand the molecular factors influencing CaM binding from a structure/function perspective. (uthscsa.edu)
  • Electron flow from reductase to oxygenase domain is controlled by calmodulin binding to canonical calmodulin binding motif located between these domains. (guidetopharmacology.org)
  • is also generated during the nitrite respiration in several bacteria, including E. coli , by the activity of nitrite reductase [ 21 ]. (sciendo.com)
  • His current research interests focus on the identification of new antimicrobial therapies and unravel the molecular mechanism underlying the transcripcional regulation of bacterial ribonucleotide reductase genes. (ibecbarcelona.eu)
  • There were three molecules of FMN for every four molecules of reductase. (tmc.edu)
  • [10] Initially, iodotyrosine deiodinase was thought to contain only one flavin mononucleotide (FMN) in each dimer, [14] but now iodotyrosine deiodinase is believed to have two FMN molecules for each homodimer. (wikidoc.org)
  • Flavodoxin and NADPH-flavodoxin reductase from Escherichia coli support bovine cytochrome P450c17 hydroxylase activities. (nih.gov)
  • Two soluble flavoproteins, purified from Escherichia coli cytosol and identified as flavodoxin and NADPH-flavodoxin (ferredoxin) reductase (flavodoxin reductase), have been found in combination to support the 17 alpha-hydroxylase activities of heterologously expressed bovine 17 alpha-hydroxylase cytochrome P450 (P450c17). (nih.gov)
  • The gene has been expressed in V. cholerae and shown to containone equivalent of covalently bound FMN. (embl-heidelberg.de)
  • His-tagged Fre reduced flavins (flavin mononucleotide [FMN] and flavin adenine dinucleotide [FAD]) and cob(III)alamin to cob(II)alamin very efficiently. (nih.gov)
  • Riboflavin consisting of two important cofactors, flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), which are involved in multiple oxidative-reduction processes and energy metabolism. (bioseek.eu)
  • Vitamin B2, or riboflavin, is a water-soluble vitamin most commonly found in the body in the form of the flavocoenzymes flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), the latter being most abundant. (medscape.com)
  • Based on the steady-state and pre-steady-state kinetic analyses of SsuE, a reaction mechanism has been elucidated for the flavin reductase catalyzed reaction in the alkanesulfonate monooxygenase system. (auburn.edu)
  • We conclude that the set point and regulation of the FMN conformational equilibrium differ markedly in eNOSr and nNOSr and can explain the lower electron transfer activity of eNOSr. (montclair.edu)
  • Physical characteristics of the two flavoproteins including absorbance spectra, molecular weights, and amino-terminal sequences are identical with those reported previously for E. coli flavodoxin and flavodoxin reductase. (nih.gov)
  • We propose that the amino acid sequence similarity between E. coli flavodoxin-flavodoxin reductase and the putative FMN, FAD, and NAD(P)H binding regions of cytochrome P450 reductase provides the basis for the reconstitution of P450c17 activities by this bacterial system. (nih.gov)
  • However, in the presence of SsuD and octanesulfonate the kinetic mechanism of SsuE is altered to a rapid equilibrium ordered mechanism, and the Km value for FMN is increased 10-fold. (auburn.edu)
  • Following the binding of FMN and NADPH to SsuE (MC-1, Michaelis complex), an initial fast phase (241 s-1) corresponds to the interaction of NADPH with FMN (CT-1, charge-transfer complex). (auburn.edu)
  • 5. Altered heme catabolism by heme oxygenase-1 caused by mutations in human NADPH cytochrome P450 reductase. (nih.gov)
  • 11. Reduction of oxaporphyrin ring of CO-bound α-verdoheme complexed with heme oxygenase-1 by NADPH-cytochrome P450 reductase. (nih.gov)
  • A crystal structure of the CaM-bound iNOS FMN-binding domain predicted a salt bridge between R536 of human iNOS and E47 of CaM. (uthscsa.edu)
  • The lack of activity and the ability of FMN to also reconstitute suggest that the redox center of FAD is essential for catalysis, rather than for structure. (tmc.edu)
  • Ribonucleotide reductases are essential enzymes which synthesize deoxyribonucleotides used in the replication of DNA. (ibecbarcelona.eu)
  • NADPH binding only stabilized the FMN-shielded conformation of nNOSr, whereas CaM shifted both enzymes toward the FMN-deshielded conformation. (montclair.edu)
  • Similarly, the conversion of vitamin B6 to the coenzyme pyridoxal 5'-phosphate needs FMN. (nih.gov)
  • After a two hour reconstitution, the reductase eluted from hydroxylapatite at the location of holoreductase. (tmc.edu)
  • 4. Involvement of NADPH in the interaction between heme oxygenase-1 and cytochrome P450 reductase. (nih.gov)
  • 8. Mass spectrometric identification of lysine residues of heme oxygenase-1 that are involved in its interaction with NADPH-cytochrome P450 reductase. (nih.gov)
  • 15. Expression and characterization of full-length human heme oxygenase-1: the presence of intact membrane-binding region leads to increased binding affinity for NADPH cytochrome P450 reductase. (nih.gov)