UNIPROT:Q8NEX9 - FACTA Search

Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Target Concepts:

Query: UNIPROT:Q8NEX9 (reductase)
26,410 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The water-soluble carbodiimide, N-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) serves as an effective reagent for cross-linking spinach leaf ferredoxin and the ferredoxin-dependent spinach leaf enzyme, glutamate synthase. The cross-linked complex was functional in the absence of added ferredoxin, suggesting that ferredoxin is cross-linked to glutamate synthase at the physiological binding site on the enzyme for this iron-sulfur protein electron donor. The ferredoxin:glutamate synthase stoichiometry of the cross-linked complex was estimated to be 2:1. The absorbance spectrum of the oxidized, cross-linked complex was very similar to that of an electrostatically stabilized, noncovalent, 2:1 complex of the two proteins. An antibody raised against spinach NADP+ reductase, which recognizes a ferredoxin-binding site on glutamate synthase, does not recognize the cross-linked ferredoxin-glutamate synthase complex. This implies that the ferredoxin-binding sites on the two enzymes are structurally similar enough so that an antibody raised against one of these ferredoxin-dependent enzymes recognizes an epitope at the ferredoxin-binding site of the second enzyme. Cross-linking of ferredoxin to its binding site on glutamate synthase renders this epitope inaccessible to the antibody.
...
PMID:The interaction of ferredoxin and glutamate synthase: cross-linking and immunological studies. 191 Feb 84

Bovine heart microsomes have been found to contain a non-heme iron protein which serves as an electron acceptor for NADPH-cytochrome P-450 reductase and therefore stimulates NADPH oxidation. This protein, tentatively referred to as Microsomal Iron Protein (MIP), has been extracted with Triton N-101 and purified by ion exchange chromatography on CM- and DEAE-celluloses and gel filtration on Sepharose 6B. MIP is an Mr = 66,000 monomer with 17 atoms of Fe(III)/molecule. Incubation with dithionite removes iron from MIP and abolishes the stimulation of NADPH oxidation, but subsequent incubation with nitrilotriacetic-Fe(III) reincorporates iron and restores the stimulation of NADPH oxidation. Oxygen is the ultimate electron acceptor. In the presence of oxygen, the enzymatic reduction of MIP Fe(III) is followed by the reoxidation of Fe(II) at the expense of oxygen, generating superoxide anion and regenerating MIP Fe(III) for the continuous oxidation of NADPH. In the absence of oxygen, electron transfer from the reductase to MIP Fe(III) causes the release of Fe(II), which limits the ability of MIP to serve as an electron acceptor and stimulate NADPH oxidation. The--NH2-terminal of MIP has been sequenced, and no homology has been found with the sequence of other iron storage or transport proteins such as ferritin or transferrin.
...
PMID:Bovine heart microsomes contain an Mr = 66,000 non-heme iron protein which stimulates NADPH oxidation. 193 64

Monospecific polyclonal rabbit antibodies to a purified form of haem oxygenase of chick liver, showing sequence similarity to mammalian haem oxygenase-1, were raised and used to study characteristics of the oxygenase. The antibodies inhibited activity of the purified oxygenase, but not other enzyme components (NADPH:cytochrome reductase and biliverdin reductase) of the standard assay mixture of haem oxygenase. In addition, the antibodies inhibited activity of haem oxygenase in microsomes (microsomal fractions) from Cd(2+)-treated chick liver, spleen, testis and brain. Western (immuno-) blots of microsomal proteins of selected organs from chick, rat and man, and homogenates of chick-embryo liver-cell cultures, probed with the antibodies, showed a major protein with a molecular mass of 33-34 kDa and a lower-molecular-mass protein (28-29 kDa) of variable intensity. Studies with trypsin and selected proteinase inhibitors established that the smaller peptide was a proteolytic product of the larger. Treatment of chick-embryo liver-cell cultures with CdCl2, a potent inducer of haem oxygenase, increased the degree of proteinase-mediated cleavage of the 33 kDa protein to the lower-molecular-mass form. These results indicate that, under at least some conditions, such cultures should be homogenized in the presence of trypsin inhibitor to prevent proteolytic degradation of the enzyme and allow maximal expression of haem oxygenase activity. The antibodies also reacted with haem oxygenase from spleen, testis and brain of both chicks and rats, and the spleen of humans. A method for quantifying the amount of haem oxygenase protein was developed with use of slot-blots and laser densitometry; linearity was observed from 0 to 5 ng of haem oxygenase protein per slot, and the method was applied to sonicated cultured chick-embryo liver cells treated with Cd2+ (0.3 mM) or iron plus glutethimide. In both cases, increases in enzyme activity were of similar magnitude to increases in amounts of enzyme protein. Approximate amounts of haem oxygenase protein in microsomes of several organs from intact animals could also be estimated by the use of slot-blot-laser densitometry, and the amounts measured were increased by the addition of purified haem oxygenase to the microsomal preparations. Results of these studies indicated that haem oxygenase-1 could be detected in microsomes from all chick or rat organs studied, including testis and brain.(ABSTRACT TRUNCATED AT 400 WORDS)
...
PMID:Immunochemical studies of haem oxygenase. Preparation and characterization of antibodies to chick liver haem oxygenase and their use in detecting and quantifying amounts of haem oxygenase protein. 195 81

Cell-free extracts of Comamonas testosteroni T-2 grown in toluene-p-sulphonate/salts medium catalyse the conversion of p-sulphobenzoate (PSB) into protocatechuate and sulphite by an NADH-requiring and Fe2(+)-activated dioxygenase. Anion-exchange chromatography of extracts yielded red (A) and yellow (B) protein fractions, both of which were necessary for dioxygenative activity. Further purification of each fraction by hydrophobic interaction chromatography and gel filtration led to two homogeneous protein components (A and B), which together converted 1 mol each of PSB, O2 and NADH into 1 mol each of protocatechuate, sulphite and, presumably, NAD+. The system was named 4-sulphobenzoate 3,4-dioxygenase (PSB dioxygenase system). Monomeric component B (Mr 36,000) was determined to be a reductase that contained 1 mol of FMN and about 2 mol each of iron and inorganic sulphur per mol. This component transferred electrons from NADH to the oxygenase component (A) or to, e.g., cytochrome c. Homodimeric component A (subunit Mr 50,000) of the PSB dioxygenase system contained one [2Fe-2S] centre per subunit and its u.v.-visible-absorption spectrum corresponded to a Rieske-type iron-sulphur centre. The requirement for activation by iron was interpreted as partial loss of mononuclear iron during purification of component A. Component A could be reduced by dithionite or by NADH plus catalytic amounts of component B. The PSB dioxygenase system displayed a narrow substrate range: none of 18 sulphonated or non-sulphonated analogues of PSB showed significant substrate-dependent O2 uptake. The physical properties of the PSB dioxygenase system resemble those of other bacterial multi-component dioxygenase, especially phthalate dioxygenase. However, it differs from most characterized systems in its overall reaction; the product is a vicinal diphenol, and not a dihydrodiol.
...
PMID:4-Sulphobenzoate 3,4-dioxygenase. Purification and properties of a desulphonative two-component enzyme system from Comamonas testosteroni T-2. 201 9

The coding characteristics of four plasmids expressing a protein (BCP) which comigrates with bacterioferritin were examined and the nucleotide sequence of a common 1985 bp segment from the 53 min region of the Escherichia coli linkage map was determined. Three open reading-frames (orf1, orf2 and orf3) were detected, and orf2 (bcp, 156 amino acid codons) appeared to encode the bacterioferritin comigratory protein, BCP. The translation product of orf3 (205 amino acid codons) resembled the iron-sulphur protein component (DMS B subunit) of the anaerobic dimethylsulphoxide reductase complex of E. coli.
...
PMID:A molecular analysis of the 53.3 minute region of the Escherichia coli linkage map. 201 88

Murine erythroleukaemia (MEL) cells are virus-transformed erythroid precursor cells that, when induced to differentiate by dimethyl sulphoxide (DMSO), will initiate haem biosynthesis by the induction and synthesis de novo of all of the enzymes of the haem-biosynthetic pathway. The activities of porphobilinogen (PBG) deaminase (EC 4.3.1.8), coproporphyrinogen oxidase (EC 1.3.3.3), protoporphyrinogen oxidase (EC 1.3.3.4), ferrochelatase (EC 4.99.1.1) and NADH:ferric iron reductase, as well as the synthesis of the enzyme ferrochelatase and the levels of excreted porphyrins, were monitored during DMSO-induced differentiation of MEL cells in culture. The data demonstrate that PBG deaminase and protoporphyrinogen oxidase activities rise rapidly and early, in comparison with ferrochelatase activity, which rises more slowly, and coproporphyrinogen oxidase activity, which decreases by 60% within 24 h of induction before returning to initial levels by 72 h. NADH:ferric iron reductase activity increases slightly, but is always present at levels higher than needed for haem synthesis. Total immunoprecipitable ferrochelatase also rises slowly and parallels the increase in its activity, suggesting that it is not synthesized early in a slowly processed precursor form. Examination of culture media demonstrated that, whereas excretion of protoporphyrin and coproporphyrin occurs within 24 h of induction, coproporphyrin is excreted in amounts 4-15 times greater than protoporphyrin.
...
PMID:Multiple mechanisms for the regulation of haem synthesis during erythroid cell differentiation. Possible role for coproporphyrinogen oxidase. 202 19

Comamonas testosteroni T-2 synthesizes an inducible enzyme system that oxygenates 4-toluene sulfontate (TS) to 4-sulfobenzyl alcohol when grown in TS-salts medium. We purified this TS methyl-monooxygenase system (TSMOS) and found it to consist of two components. A monomeric, iron-sulfur flavoprotein (component B), which has been shown to act as a reductase in the 4-sulfobenzoate dioxygenase system of this organism (H. H. Locher, T. Leisinger, and A. M. Cook, Biochem. J. 274:833-842, 1991), carried electrons from NADH to component M, an oxygenase. This oxygenase had the UV-visible spectral characteristics of an iron-sulfur protein. Mrs of about 152,000 for the native oxygenase and of 43,000 under denaturing conditions indicated a homotri- or homotetrameric enzyme, whose N-terminal amino acids and amino acid composition were determined. The activity of the purified enzyme was enhanced about fivefold by the addition of Fe2+. In the presence of O2 and NADH, components B and M together catalyzed the stoichiometric transformation of TS or p-toluate to the corresponding alcohol. The reaction was confirmed as oxygenation of the methyl group by observation of an oxygen atom from 18O2 in carboxybenzyl alcohol. The substrate range of TSMOS included carboxylated analogs of TS (p- and m-toluates and 4-ethylbenzoate), whereas p-xylene, toluene, and p-cresol were not substrates. TSMOS also catalyzed demethylation; 4-methoxybenzoate was transformed to 4-hydroxybenzoate and formaldehyde.
...
PMID:4-Toluene sulfonate methyl-monooxygenase from Comamonas testosteroni T-2: purification and some properties of the oxygenase component. 205 Jun 32

Under anaerobic circumstances in the presence of nitrate Paracoccus denitrificans is able to denitrify. The properties of the reductases involved in nitrate reductase, nitrite reductase, nitric oxide reductase, and nitrous oxide reductase are described. For that purpose not only the properties of the enzymes of P. denitrificans are considered but also those from Escherichia coli, Pseudomonas aeruginosa, and Pseudomonas stutzeri. Nitrate reductase consists of three subunits: the alpha subunit contains the molybdenum cofactor, the beta subunit contains the iron sulfur clusters, and the gamma subunit is a special cytochrome b. Nitrate is reduced at the cytoplasmic side of the membrane and evidence for the presence of a nitrate-nitrite antiporter is presented. Electron flow is from ubiquinol via the specific cytochrome b to the nitrate reductase. Nitrite reductase (which is identical to cytochrome cd1) and nitrous oxide reductase are periplasmic proteins. Nitric oxide reductase is a membrane-bound enzyme. The bc1 complex is involved in electron flow to these reductases and the whole reaction takes place at the periplasmic side of the membrane. It is now firmly established that NO is an obligatory intermediate between nitrite and nitrous oxide. Nitrous oxide reductase is a multi-copper protein. A large number of genes is involved in the acquisition of molybdenum and copper, the formation of the molybdenum cofactor, and the insertion of the metals. It is estimated that at least 40 genes are involved in the process of denitrification. The control of the expression of these genes in P. denitrificans is totally unknown. As an example of such complex regulatory systems the function of the fnr, narX, and narL gene products in the expression of nitrate reductase in E. coli is described. The control of the effects of oxygen on the reduction of nitrate, nitrite, and nitrous oxide are discussed. Oxygen inhibits reduction of nitrate by prevention of nitrate uptake in the cell. In the case of nitrite and nitrous oxide a competition between reductases and oxidases for a limited supply of electrons from primary dehydrogenases seems to play an important role. Under some circumstances NO formed from nitrite may inhibit oxidases, resulting in a redistribution of electron flow from oxygen to nitrite. P. denitrificans contains three main oxidases: cytochrome aa3, cytochrome o, and cytochrome co. Cytochrome o is proton translocating and receives its electrons from ubiquinol. Some properties of cytochrome co, which receives its electrons from cytochrome c, are reported.(ABSTRACT TRUNCATED AT 400 WORDS)
...
PMID:Metabolic regulation including anaerobic metabolism in Paracoccus denitrificans. 205 Jun 53

Cytochrome P-460 of Nitrosomonas europaea [Erickson, R.H. and Hooper, A.B. (1972) Biochim. Biophys. Acta 275, 231-244] was further purified to an electrophoretically homogeneous state. The cytochrome molecule was composed of three molecules of subunits with Mr of 17,300-18,500, and contained three atoms of iron, which seemed to be heme iron, and six cysteine residues, but did not contain nonheme iron or inorganic sulfide. The cytochrome showed absorption peaks at 460 and 688 nm with a broad shoulder at 635 nm in the reduced form. The ESR spectrum of ferricytochrome P-460 showed signals at g = 5.91, 5.63, and 1.99, indicating that the protein was a high spin hemoprotein. The heme of the cytochrome was not cleaved by the methods which were available for cleavage of heme c. The pyridine ferrohemochrome of the hemoprotein did not show the distinct alpha and beta peaks which are shown by the ferrohemochromes of many other cytochromes so far known. The N-terminal amino acid sequence of cytochrome P-460 differed from that of hydroxylamine oxidoreductase. Therefore, cytochrome P-460 did not seem to be the solubilized P-460 moiety of hydroxylamine oxidoreductase, in agreement with the finding by D.J. Miller et al. [J. Gen. Microbiol. 130, 3049-3054 (1984)]. However, cytochrome P-460 had several enzymatic activities which hydroxylamine oxidoreductase showed. Although most of the activities of the cytochrome were lower than the corresponding activities of the oxidoreductase, the hydroxylamine-cytochrome c-552 reductase activity of the cytochrome was about 5-times as high as that of the oxidoreductase.
...
PMID:Cytochrome P-460 of Nitrosomonas europaea: further purification and further characterization. 208 33

The level of quinone oxidoreductases (microsomal and cytosolic DT-diaphorase, NADPH-cytochrome P450 reductase and NADH-cytochrome b5 reductase), superoxide dismutase and glutathione-related enzymatic activities in diethylstilbestrol (DES)-induced carcinogenesis in kidney from Syrian golden hamsters are presented. Animals that exhibited two different stages of DES-induced carcinogenesis in kidney--pre- and neoplastic lesions and tumorous lesions (after 6 and 8 months of continuous exposure to DES respectively)--were studied in comparison to kidneys from control animals. A dramatic decrease in microsomal and cytosolic DT-diaphorase activities (13.6 and 37.8% of controls), as well as in glutathione disulphide reductase (39.5%), and less marked in superoxide dismutase (45.6%), NADH cytochrome b5 reductase (61.9%) glutathione transferase (GST) towards 1-chloro-2,4-dinitrobenzene (CDNB) (66.2%) and glutathione peroxidase (GSH-Px) (80%) activities, were observed in kidneys with pre- and neoplastic lesions. NADPH-cytochrome P450 reductase and GST activity towards 4-hydroxy-2,3-trans-nonenal (4-HNE) showed no statistically significant variation at this stage of carcinogenesis. In kidney from animals with tumorous lesions, all the enzymatic activities mentioned above decreased, except for superoxide dismutase, which was increased to 186% of the control activity. GST activity towards 4-HNE again showed no statistically significant variation. These results suggest that if one-electron reduction of diethylstilbestrol-4',4''-quinone (DESQ) occurs, it may play a very important role in the development of DES carcinogenesis (pre- and neoplastic lesions), since at this stage of carcinogenesis the primary defense mechanisms against the oxygen free radicals generated in this way, i.e. SOD activity, is reduced to less than a half of control values. Both cytosolic and microsomal DT-diaphorase activities are unable at this stage of carcinogenesis to promote effectively the two-electron reduction of DESQ, which would avoid the initial formation of superoxide anion. The consequences of these decreases may be an increased steady-state concentration of superoxide anion and hydrogen peroxide, which in the presence of iron might lead to lipid peroxidation. GST activity towards 4-HNE could be responsible for the possible higher steady-state concentration of this lipid peroxidation product during DES treatment. The induction of DT-diaphorase and its protective role in the prevention of the development of pre- and neoplastic lesions in kidney from Syrian golden hamster during DES treatment is also discussed.
...
PMID:The levels of quinone reductases, superoxide dismutase and glutathione-related enzymatic activities in diethylstilbestrol-induced carcinogenesis in the kidney of male Syrian golden hamsters. 211 5

<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>